index.js

(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
  typeof define === 'function' && define.amd ? define(['exports'], factory) :
  (global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.csv_stringify = {}));
})(this, (function (exports) { 'use strict';

  var domain;

  // This constructor is used to store event handlers. Instantiating this is
  // faster than explicitly calling `Object.create(null)` to get a "clean" empty
  // object (tested with v8 v4.9).
  function EventHandlers() {}
  EventHandlers.prototype = Object.create(null);

  function EventEmitter() {
    EventEmitter.init.call(this);
  }

  // nodejs oddity
  // require('events') === require('events').EventEmitter
  EventEmitter.EventEmitter = EventEmitter;

  EventEmitter.usingDomains = false;

  EventEmitter.prototype.domain = undefined;
  EventEmitter.prototype._events = undefined;
  EventEmitter.prototype._maxListeners = undefined;

  // By default EventEmitters will print a warning if more than 10 listeners are
  // added to it. This is a useful default which helps finding memory leaks.
  EventEmitter.defaultMaxListeners = 10;

  EventEmitter.init = function() {
    this.domain = null;
    if (EventEmitter.usingDomains) {
      // if there is an active domain, then attach to it.
      if (domain.active ) ;
    }

    if (!this._events || this._events === Object.getPrototypeOf(this)._events) {
      this._events = new EventHandlers();
      this._eventsCount = 0;
    }

    this._maxListeners = this._maxListeners || undefined;
  };

  // Obviously not all Emitters should be limited to 10. This function allows
  // that to be increased. Set to zero for unlimited.
  EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
    if (typeof n !== 'number' || n < 0 || isNaN(n))
      throw new TypeError('"n" argument must be a positive number');
    this._maxListeners = n;
    return this;
  };

  function $getMaxListeners(that) {
    if (that._maxListeners === undefined)
      return EventEmitter.defaultMaxListeners;
    return that._maxListeners;
  }

  EventEmitter.prototype.getMaxListeners = function getMaxListeners() {
    return $getMaxListeners(this);
  };

  // These standalone emit* functions are used to optimize calling of event
  // handlers for fast cases because emit() itself often has a variable number of
  // arguments and can be deoptimized because of that. These functions always have
  // the same number of arguments and thus do not get deoptimized, so the code
  // inside them can execute faster.
  function emitNone(handler, isFn, self) {
    if (isFn)
      handler.call(self);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self);
    }
  }
  function emitOne(handler, isFn, self, arg1) {
    if (isFn)
      handler.call(self, arg1);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1);
    }
  }
  function emitTwo(handler, isFn, self, arg1, arg2) {
    if (isFn)
      handler.call(self, arg1, arg2);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1, arg2);
    }
  }
  function emitThree(handler, isFn, self, arg1, arg2, arg3) {
    if (isFn)
      handler.call(self, arg1, arg2, arg3);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1, arg2, arg3);
    }
  }

  function emitMany(handler, isFn, self, args) {
    if (isFn)
      handler.apply(self, args);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].apply(self, args);
    }
  }

  EventEmitter.prototype.emit = function emit(type) {
    var er, handler, len, args, i, events, domain;
    var doError = (type === 'error');

    events = this._events;
    if (events)
      doError = (doError && events.error == null);
    else if (!doError)
      return false;

    domain = this.domain;

    // If there is no 'error' event listener then throw.
    if (doError) {
      er = arguments[1];
      if (domain) {
        if (!er)
          er = new Error('Uncaught, unspecified "error" event');
        er.domainEmitter = this;
        er.domain = domain;
        er.domainThrown = false;
        domain.emit('error', er);
      } else if (er instanceof Error) {
        throw er; // Unhandled 'error' event
      } else {
        // At least give some kind of context to the user
        var err = new Error('Uncaught, unspecified "error" event. (' + er + ')');
        err.context = er;
        throw err;
      }
      return false;
    }

    handler = events[type];

    if (!handler)
      return false;

    var isFn = typeof handler === 'function';
    len = arguments.length;
    switch (len) {
      // fast cases
      case 1:
        emitNone(handler, isFn, this);
        break;
      case 2:
        emitOne(handler, isFn, this, arguments[1]);
        break;
      case 3:
        emitTwo(handler, isFn, this, arguments[1], arguments[2]);
        break;
      case 4:
        emitThree(handler, isFn, this, arguments[1], arguments[2], arguments[3]);
        break;
      // slower
      default:
        args = new Array(len - 1);
        for (i = 1; i < len; i++)
          args[i - 1] = arguments[i];
        emitMany(handler, isFn, this, args);
    }

    return true;
  };

  function _addListener(target, type, listener, prepend) {
    var m;
    var events;
    var existing;

    if (typeof listener !== 'function')
      throw new TypeError('"listener" argument must be a function');

    events = target._events;
    if (!events) {
      events = target._events = new EventHandlers();
      target._eventsCount = 0;
    } else {
      // To avoid recursion in the case that type === "newListener"! Before
      // adding it to the listeners, first emit "newListener".
      if (events.newListener) {
        target.emit('newListener', type,
                    listener.listener ? listener.listener : listener);

        // Re-assign `events` because a newListener handler could have caused the
        // this._events to be assigned to a new object
        events = target._events;
      }
      existing = events[type];
    }

    if (!existing) {
      // Optimize the case of one listener. Don't need the extra array object.
      existing = events[type] = listener;
      ++target._eventsCount;
    } else {
      if (typeof existing === 'function') {
        // Adding the second element, need to change to array.
        existing = events[type] = prepend ? [listener, existing] :
                                            [existing, listener];
      } else {
        // If we've already got an array, just append.
        if (prepend) {
          existing.unshift(listener);
        } else {
          existing.push(listener);
        }
      }

      // Check for listener leak
      if (!existing.warned) {
        m = $getMaxListeners(target);
        if (m && m > 0 && existing.length > m) {
          existing.warned = true;
          var w = new Error('Possible EventEmitter memory leak detected. ' +
                              existing.length + ' ' + type + ' listeners added. ' +
                              'Use emitter.setMaxListeners() to increase limit');
          w.name = 'MaxListenersExceededWarning';
          w.emitter = target;
          w.type = type;
          w.count = existing.length;
          emitWarning(w);
        }
      }
    }

    return target;
  }
  function emitWarning(e) {
    typeof console.warn === 'function' ? console.warn(e) : console.log(e);
  }
  EventEmitter.prototype.addListener = function addListener(type, listener) {
    return _addListener(this, type, listener, false);
  };

  EventEmitter.prototype.on = EventEmitter.prototype.addListener;

  EventEmitter.prototype.prependListener =
      function prependListener(type, listener) {
        return _addListener(this, type, listener, true);
      };

  function _onceWrap(target, type, listener) {
    var fired = false;
    function g() {
      target.removeListener(type, g);
      if (!fired) {
        fired = true;
        listener.apply(target, arguments);
      }
    }
    g.listener = listener;
    return g;
  }

  EventEmitter.prototype.once = function once(type, listener) {
    if (typeof listener !== 'function')
      throw new TypeError('"listener" argument must be a function');
    this.on(type, _onceWrap(this, type, listener));
    return this;
  };

  EventEmitter.prototype.prependOnceListener =
      function prependOnceListener(type, listener) {
        if (typeof listener !== 'function')
          throw new TypeError('"listener" argument must be a function');
        this.prependListener(type, _onceWrap(this, type, listener));
        return this;
      };

  // emits a 'removeListener' event iff the listener was removed
  EventEmitter.prototype.removeListener =
      function removeListener(type, listener) {
        var list, events, position, i, originalListener;

        if (typeof listener !== 'function')
          throw new TypeError('"listener" argument must be a function');

        events = this._events;
        if (!events)
          return this;

        list = events[type];
        if (!list)
          return this;

        if (list === listener || (list.listener && list.listener === listener)) {
          if (--this._eventsCount === 0)
            this._events = new EventHandlers();
          else {
            delete events[type];
            if (events.removeListener)
              this.emit('removeListener', type, list.listener || listener);
          }
        } else if (typeof list !== 'function') {
          position = -1;

          for (i = list.length; i-- > 0;) {
            if (list[i] === listener ||
                (list[i].listener && list[i].listener === listener)) {
              originalListener = list[i].listener;
              position = i;
              break;
            }
          }

          if (position < 0)
            return this;

          if (list.length === 1) {
            list[0] = undefined;
            if (--this._eventsCount === 0) {
              this._events = new EventHandlers();
              return this;
            } else {
              delete events[type];
            }
          } else {
            spliceOne(list, position);
          }

          if (events.removeListener)
            this.emit('removeListener', type, originalListener || listener);
        }

        return this;
      };

  EventEmitter.prototype.removeAllListeners =
      function removeAllListeners(type) {
        var listeners, events;

        events = this._events;
        if (!events)
          return this;

        // not listening for removeListener, no need to emit
        if (!events.removeListener) {
          if (arguments.length === 0) {
            this._events = new EventHandlers();
            this._eventsCount = 0;
          } else if (events[type]) {
            if (--this._eventsCount === 0)
              this._events = new EventHandlers();
            else
              delete events[type];
          }
          return this;
        }

        // emit removeListener for all listeners on all events
        if (arguments.length === 0) {
          var keys = Object.keys(events);
          for (var i = 0, key; i < keys.length; ++i) {
            key = keys[i];
            if (key === 'removeListener') continue;
            this.removeAllListeners(key);
          }
          this.removeAllListeners('removeListener');
          this._events = new EventHandlers();
          this._eventsCount = 0;
          return this;
        }

        listeners = events[type];

        if (typeof listeners === 'function') {
          this.removeListener(type, listeners);
        } else if (listeners) {
          // LIFO order
          do {
            this.removeListener(type, listeners[listeners.length - 1]);
          } while (listeners[0]);
        }

        return this;
      };

  EventEmitter.prototype.listeners = function listeners(type) {
    var evlistener;
    var ret;
    var events = this._events;

    if (!events)
      ret = [];
    else {
      evlistener = events[type];
      if (!evlistener)
        ret = [];
      else if (typeof evlistener === 'function')
        ret = [evlistener.listener || evlistener];
      else
        ret = unwrapListeners(evlistener);
    }

    return ret;
  };

  EventEmitter.listenerCount = function(emitter, type) {
    if (typeof emitter.listenerCount === 'function') {
      return emitter.listenerCount(type);
    } else {
      return listenerCount$1.call(emitter, type);
    }
  };

  EventEmitter.prototype.listenerCount = listenerCount$1;
  function listenerCount$1(type) {
    var events = this._events;

    if (events) {
      var evlistener = events[type];

      if (typeof evlistener === 'function') {
        return 1;
      } else if (evlistener) {
        return evlistener.length;
      }
    }

    return 0;
  }

  EventEmitter.prototype.eventNames = function eventNames() {
    return this._eventsCount > 0 ? Reflect.ownKeys(this._events) : [];
  };

  // About 1.5x faster than the two-arg version of Array#splice().
  function spliceOne(list, index) {
    for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
      list[i] = list[k];
    list.pop();
  }

  function arrayClone(arr, i) {
    var copy = new Array(i);
    while (i--)
      copy[i] = arr[i];
    return copy;
  }

  function unwrapListeners(arr) {
    var ret = new Array(arr.length);
    for (var i = 0; i < ret.length; ++i) {
      ret[i] = arr[i].listener || arr[i];
    }
    return ret;
  }

  var global$1 = (typeof global !== "undefined" ? global :
              typeof self !== "undefined" ? self :
              typeof window !== "undefined" ? window : {});

  var lookup = [];
  var revLookup = [];
  var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array;
  var inited = false;
  function init () {
    inited = true;
    var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    for (var i = 0, len = code.length; i < len; ++i) {
      lookup[i] = code[i];
      revLookup[code.charCodeAt(i)] = i;
    }

    revLookup['-'.charCodeAt(0)] = 62;
    revLookup['_'.charCodeAt(0)] = 63;
  }

  function toByteArray (b64) {
    if (!inited) {
      init();
    }
    var i, j, l, tmp, placeHolders, arr;
    var len = b64.length;

    if (len % 4 > 0) {
      throw new Error('Invalid string. Length must be a multiple of 4')
    }

    // the number of equal signs (place holders)
    // if there are two placeholders, than the two characters before it
    // represent one byte
    // if there is only one, then the three characters before it represent 2 bytes
    // this is just a cheap hack to not do indexOf twice
    placeHolders = b64[len - 2] === '=' ? 2 : b64[len - 1] === '=' ? 1 : 0;

    // base64 is 4/3 + up to two characters of the original data
    arr = new Arr(len * 3 / 4 - placeHolders);

    // if there are placeholders, only get up to the last complete 4 chars
    l = placeHolders > 0 ? len - 4 : len;

    var L = 0;

    for (i = 0, j = 0; i < l; i += 4, j += 3) {
      tmp = (revLookup[b64.charCodeAt(i)] << 18) | (revLookup[b64.charCodeAt(i + 1)] << 12) | (revLookup[b64.charCodeAt(i + 2)] << 6) | revLookup[b64.charCodeAt(i + 3)];
      arr[L++] = (tmp >> 16) & 0xFF;
      arr[L++] = (tmp >> 8) & 0xFF;
      arr[L++] = tmp & 0xFF;
    }

    if (placeHolders === 2) {
      tmp = (revLookup[b64.charCodeAt(i)] << 2) | (revLookup[b64.charCodeAt(i + 1)] >> 4);
      arr[L++] = tmp & 0xFF;
    } else if (placeHolders === 1) {
      tmp = (revLookup[b64.charCodeAt(i)] << 10) | (revLookup[b64.charCodeAt(i + 1)] << 4) | (revLookup[b64.charCodeAt(i + 2)] >> 2);
      arr[L++] = (tmp >> 8) & 0xFF;
      arr[L++] = tmp & 0xFF;
    }

    return arr
  }

  function tripletToBase64 (num) {
    return lookup[num >> 18 & 0x3F] + lookup[num >> 12 & 0x3F] + lookup[num >> 6 & 0x3F] + lookup[num & 0x3F]
  }

  function encodeChunk (uint8, start, end) {
    var tmp;
    var output = [];
    for (var i = start; i < end; i += 3) {
      tmp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2]);
      output.push(tripletToBase64(tmp));
    }
    return output.join('')
  }

  function fromByteArray (uint8) {
    if (!inited) {
      init();
    }
    var tmp;
    var len = uint8.length;
    var extraBytes = len % 3; // if we have 1 byte left, pad 2 bytes
    var output = '';
    var parts = [];
    var maxChunkLength = 16383; // must be multiple of 3

    // go through the array every three bytes, we'll deal with trailing stuff later
    for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
      parts.push(encodeChunk(uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength)));
    }

    // pad the end with zeros, but make sure to not forget the extra bytes
    if (extraBytes === 1) {
      tmp = uint8[len - 1];
      output += lookup[tmp >> 2];
      output += lookup[(tmp << 4) & 0x3F];
      output += '==';
    } else if (extraBytes === 2) {
      tmp = (uint8[len - 2] << 8) + (uint8[len - 1]);
      output += lookup[tmp >> 10];
      output += lookup[(tmp >> 4) & 0x3F];
      output += lookup[(tmp << 2) & 0x3F];
      output += '=';
    }

    parts.push(output);

    return parts.join('')
  }

  function read (buffer, offset, isLE, mLen, nBytes) {
    var e, m;
    var eLen = nBytes * 8 - mLen - 1;
    var eMax = (1 << eLen) - 1;
    var eBias = eMax >> 1;
    var nBits = -7;
    var i = isLE ? (nBytes - 1) : 0;
    var d = isLE ? -1 : 1;
    var s = buffer[offset + i];

    i += d;

    e = s & ((1 << (-nBits)) - 1);
    s >>= (-nBits);
    nBits += eLen;
    for (; nBits > 0; e = e * 256 + buffer[offset + i], i += d, nBits -= 8) {}

    m = e & ((1 << (-nBits)) - 1);
    e >>= (-nBits);
    nBits += mLen;
    for (; nBits > 0; m = m * 256 + buffer[offset + i], i += d, nBits -= 8) {}

    if (e === 0) {
      e = 1 - eBias;
    } else if (e === eMax) {
      return m ? NaN : ((s ? -1 : 1) * Infinity)
    } else {
      m = m + Math.pow(2, mLen);
      e = e - eBias;
    }
    return (s ? -1 : 1) * m * Math.pow(2, e - mLen)
  }

  function write (buffer, value, offset, isLE, mLen, nBytes) {
    var e, m, c;
    var eLen = nBytes * 8 - mLen - 1;
    var eMax = (1 << eLen) - 1;
    var eBias = eMax >> 1;
    var rt = (mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0);
    var i = isLE ? 0 : (nBytes - 1);
    var d = isLE ? 1 : -1;
    var s = value < 0 || (value === 0 && 1 / value < 0) ? 1 : 0;

    value = Math.abs(value);

    if (isNaN(value) || value === Infinity) {
      m = isNaN(value) ? 1 : 0;
      e = eMax;
    } else {
      e = Math.floor(Math.log(value) / Math.LN2);
      if (value * (c = Math.pow(2, -e)) < 1) {
        e--;
        c *= 2;
      }
      if (e + eBias >= 1) {
        value += rt / c;
      } else {
        value += rt * Math.pow(2, 1 - eBias);
      }
      if (value * c >= 2) {
        e++;
        c /= 2;
      }

      if (e + eBias >= eMax) {
        m = 0;
        e = eMax;
      } else if (e + eBias >= 1) {
        m = (value * c - 1) * Math.pow(2, mLen);
        e = e + eBias;
      } else {
        m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen);
        e = 0;
      }
    }

    for (; mLen >= 8; buffer[offset + i] = m & 0xff, i += d, m /= 256, mLen -= 8) {}

    e = (e << mLen) | m;
    eLen += mLen;
    for (; eLen > 0; buffer[offset + i] = e & 0xff, i += d, e /= 256, eLen -= 8) {}

    buffer[offset + i - d] |= s * 128;
  }

  var toString = {}.toString;

  var isArray$1 = Array.isArray || function (arr) {
    return toString.call(arr) == '[object Array]';
  };

  var INSPECT_MAX_BYTES = 50;

  /**
   * If `Buffer.TYPED_ARRAY_SUPPORT`:
   *   === true    Use Uint8Array implementation (fastest)
   *   === false   Use Object implementation (most compatible, even IE6)
   *
   * Browsers that support typed arrays are IE 10+, Firefox 4+, Chrome 7+, Safari 5.1+,
   * Opera 11.6+, iOS 4.2+.
   *
   * Due to various browser bugs, sometimes the Object implementation will be used even
   * when the browser supports typed arrays.
   *
   * Note:
   *
   *   - Firefox 4-29 lacks support for adding new properties to `Uint8Array` instances,
   *     See: https://bugzilla.mozilla.org/show_bug.cgi?id=695438.
   *
   *   - Chrome 9-10 is missing the `TypedArray.prototype.subarray` function.
   *
   *   - IE10 has a broken `TypedArray.prototype.subarray` function which returns arrays of
   *     incorrect length in some situations.

   * We detect these buggy browsers and set `Buffer.TYPED_ARRAY_SUPPORT` to `false` so they
   * get the Object implementation, which is slower but behaves correctly.
   */
  Buffer.TYPED_ARRAY_SUPPORT = global$1.TYPED_ARRAY_SUPPORT !== undefined
    ? global$1.TYPED_ARRAY_SUPPORT
    : true;

  /*
   * Export kMaxLength after typed array support is determined.
   */
  kMaxLength();

  function kMaxLength () {
    return Buffer.TYPED_ARRAY_SUPPORT
      ? 0x7fffffff
      : 0x3fffffff
  }

  function createBuffer (that, length) {
    if (kMaxLength() < length) {
      throw new RangeError('Invalid typed array length')
    }
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      // Return an augmented `Uint8Array` instance, for best performance
      that = new Uint8Array(length);
      that.__proto__ = Buffer.prototype;
    } else {
      // Fallback: Return an object instance of the Buffer class
      if (that === null) {
        that = new Buffer(length);
      }
      that.length = length;
    }

    return that
  }

  /**
   * The Buffer constructor returns instances of `Uint8Array` that have their
   * prototype changed to `Buffer.prototype`. Furthermore, `Buffer` is a subclass of
   * `Uint8Array`, so the returned instances will have all the node `Buffer` methods
   * and the `Uint8Array` methods. Square bracket notation works as expected -- it
   * returns a single octet.
   *
   * The `Uint8Array` prototype remains unmodified.
   */

  function Buffer (arg, encodingOrOffset, length) {
    if (!Buffer.TYPED_ARRAY_SUPPORT && !(this instanceof Buffer)) {
      return new Buffer(arg, encodingOrOffset, length)
    }

    // Common case.
    if (typeof arg === 'number') {
      if (typeof encodingOrOffset === 'string') {
        throw new Error(
          'If encoding is specified then the first argument must be a string'
        )
      }
      return allocUnsafe(this, arg)
    }
    return from(this, arg, encodingOrOffset, length)
  }

  Buffer.poolSize = 8192; // not used by this implementation

  // TODO: Legacy, not needed anymore. Remove in next major version.
  Buffer._augment = function (arr) {
    arr.__proto__ = Buffer.prototype;
    return arr
  };

  function from (that, value, encodingOrOffset, length) {
    if (typeof value === 'number') {
      throw new TypeError('"value" argument must not be a number')
    }

    if (typeof ArrayBuffer !== 'undefined' && value instanceof ArrayBuffer) {
      return fromArrayBuffer(that, value, encodingOrOffset, length)
    }

    if (typeof value === 'string') {
      return fromString(that, value, encodingOrOffset)
    }

    return fromObject(that, value)
  }

  /**
   * Functionally equivalent to Buffer(arg, encoding) but throws a TypeError
   * if value is a number.
   * Buffer.from(str[, encoding])
   * Buffer.from(array)
   * Buffer.from(buffer)
   * Buffer.from(arrayBuffer[, byteOffset[, length]])
   **/
  Buffer.from = function (value, encodingOrOffset, length) {
    return from(null, value, encodingOrOffset, length)
  };

  if (Buffer.TYPED_ARRAY_SUPPORT) {
    Buffer.prototype.__proto__ = Uint8Array.prototype;
    Buffer.__proto__ = Uint8Array;
    if (typeof Symbol !== 'undefined' && Symbol.species &&
        Buffer[Symbol.species] === Buffer) ;
  }

  function assertSize (size) {
    if (typeof size !== 'number') {
      throw new TypeError('"size" argument must be a number')
    } else if (size < 0) {
      throw new RangeError('"size" argument must not be negative')
    }
  }

  function alloc (that, size, fill, encoding) {
    assertSize(size);
    if (size <= 0) {
      return createBuffer(that, size)
    }
    if (fill !== undefined) {
      // Only pay attention to encoding if it's a string. This
      // prevents accidentally sending in a number that would
      // be interpretted as a start offset.
      return typeof encoding === 'string'
        ? createBuffer(that, size).fill(fill, encoding)
        : createBuffer(that, size).fill(fill)
    }
    return createBuffer(that, size)
  }

  /**
   * Creates a new filled Buffer instance.
   * alloc(size[, fill[, encoding]])
   **/
  Buffer.alloc = function (size, fill, encoding) {
    return alloc(null, size, fill, encoding)
  };

  function allocUnsafe (that, size) {
    assertSize(size);
    that = createBuffer(that, size < 0 ? 0 : checked(size) | 0);
    if (!Buffer.TYPED_ARRAY_SUPPORT) {
      for (var i = 0; i < size; ++i) {
        that[i] = 0;
      }
    }
    return that
  }

  /**
   * Equivalent to Buffer(num), by default creates a non-zero-filled Buffer instance.
   * */
  Buffer.allocUnsafe = function (size) {
    return allocUnsafe(null, size)
  };
  /**
   * Equivalent to SlowBuffer(num), by default creates a non-zero-filled Buffer instance.
   */
  Buffer.allocUnsafeSlow = function (size) {
    return allocUnsafe(null, size)
  };

  function fromString (that, string, encoding) {
    if (typeof encoding !== 'string' || encoding === '') {
      encoding = 'utf8';
    }

    if (!Buffer.isEncoding(encoding)) {
      throw new TypeError('"encoding" must be a valid string encoding')
    }

    var length = byteLength(string, encoding) | 0;
    that = createBuffer(that, length);

    var actual = that.write(string, encoding);

    if (actual !== length) {
      // Writing a hex string, for example, that contains invalid characters will
      // cause everything after the first invalid character to be ignored. (e.g.
      // 'abxxcd' will be treated as 'ab')
      that = that.slice(0, actual);
    }

    return that
  }

  function fromArrayLike (that, array) {
    var length = array.length < 0 ? 0 : checked(array.length) | 0;
    that = createBuffer(that, length);
    for (var i = 0; i < length; i += 1) {
      that[i] = array[i] & 255;
    }
    return that
  }

  function fromArrayBuffer (that, array, byteOffset, length) {
    array.byteLength; // this throws if `array` is not a valid ArrayBuffer

    if (byteOffset < 0 || array.byteLength < byteOffset) {
      throw new RangeError('\'offset\' is out of bounds')
    }

    if (array.byteLength < byteOffset + (length || 0)) {
      throw new RangeError('\'length\' is out of bounds')
    }

    if (byteOffset === undefined && length === undefined) {
      array = new Uint8Array(array);
    } else if (length === undefined) {
      array = new Uint8Array(array, byteOffset);
    } else {
      array = new Uint8Array(array, byteOffset, length);
    }

    if (Buffer.TYPED_ARRAY_SUPPORT) {
      // Return an augmented `Uint8Array` instance, for best performance
      that = array;
      that.__proto__ = Buffer.prototype;
    } else {
      // Fallback: Return an object instance of the Buffer class
      that = fromArrayLike(that, array);
    }
    return that
  }

  function fromObject (that, obj) {
    if (internalIsBuffer(obj)) {
      var len = checked(obj.length) | 0;
      that = createBuffer(that, len);

      if (that.length === 0) {
        return that
      }

      obj.copy(that, 0, 0, len);
      return that
    }

    if (obj) {
      if ((typeof ArrayBuffer !== 'undefined' &&
          obj.buffer instanceof ArrayBuffer) || 'length' in obj) {
        if (typeof obj.length !== 'number' || isnan(obj.length)) {
          return createBuffer(that, 0)
        }
        return fromArrayLike(that, obj)
      }

      if (obj.type === 'Buffer' && isArray$1(obj.data)) {
        return fromArrayLike(that, obj.data)
      }
    }

    throw new TypeError('First argument must be a string, Buffer, ArrayBuffer, Array, or array-like object.')
  }

  function checked (length) {
    // Note: cannot use `length < kMaxLength()` here because that fails when
    // length is NaN (which is otherwise coerced to zero.)
    if (length >= kMaxLength()) {
      throw new RangeError('Attempt to allocate Buffer larger than maximum ' +
                           'size: 0x' + kMaxLength().toString(16) + ' bytes')
    }
    return length | 0
  }
  Buffer.isBuffer = isBuffer;
  function internalIsBuffer (b) {
    return !!(b != null && b._isBuffer)
  }

  Buffer.compare = function compare (a, b) {
    if (!internalIsBuffer(a) || !internalIsBuffer(b)) {
      throw new TypeError('Arguments must be Buffers')
    }

    if (a === b) return 0

    var x = a.length;
    var y = b.length;

    for (var i = 0, len = Math.min(x, y); i < len; ++i) {
      if (a[i] !== b[i]) {
        x = a[i];
        y = b[i];
        break
      }
    }

    if (x < y) return -1
    if (y < x) return 1
    return 0
  };

  Buffer.isEncoding = function isEncoding (encoding) {
    switch (String(encoding).toLowerCase()) {
      case 'hex':
      case 'utf8':
      case 'utf-8':
      case 'ascii':
      case 'latin1':
      case 'binary':
      case 'base64':
      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return true
      default:
        return false
    }
  };

  Buffer.concat = function concat (list, length) {
    if (!isArray$1(list)) {
      throw new TypeError('"list" argument must be an Array of Buffers')
    }

    if (list.length === 0) {
      return Buffer.alloc(0)
    }

    var i;
    if (length === undefined) {
      length = 0;
      for (i = 0; i < list.length; ++i) {
        length += list[i].length;
      }
    }

    var buffer = Buffer.allocUnsafe(length);
    var pos = 0;
    for (i = 0; i < list.length; ++i) {
      var buf = list[i];
      if (!internalIsBuffer(buf)) {
        throw new TypeError('"list" argument must be an Array of Buffers')
      }
      buf.copy(buffer, pos);
      pos += buf.length;
    }
    return buffer
  };

  function byteLength (string, encoding) {
    if (internalIsBuffer(string)) {
      return string.length
    }
    if (typeof ArrayBuffer !== 'undefined' && typeof ArrayBuffer.isView === 'function' &&
        (ArrayBuffer.isView(string) || string instanceof ArrayBuffer)) {
      return string.byteLength
    }
    if (typeof string !== 'string') {
      string = '' + string;
    }

    var len = string.length;
    if (len === 0) return 0

    // Use a for loop to avoid recursion
    var loweredCase = false;
    for (;;) {
      switch (encoding) {
        case 'ascii':
        case 'latin1':
        case 'binary':
          return len
        case 'utf8':
        case 'utf-8':
        case undefined:
          return utf8ToBytes(string).length
        case 'ucs2':
        case 'ucs-2':
        case 'utf16le':
        case 'utf-16le':
          return len * 2
        case 'hex':
          return len >>> 1
        case 'base64':
          return base64ToBytes(string).length
        default:
          if (loweredCase) return utf8ToBytes(string).length // assume utf8
          encoding = ('' + encoding).toLowerCase();
          loweredCase = true;
      }
    }
  }
  Buffer.byteLength = byteLength;

  function slowToString (encoding, start, end) {
    var loweredCase = false;

    // No need to verify that "this.length <= MAX_UINT32" since it's a read-only
    // property of a typed array.

    // This behaves neither like String nor Uint8Array in that we set start/end
    // to their upper/lower bounds if the value passed is out of range.
    // undefined is handled specially as per ECMA-262 6th Edition,
    // Section 13.3.3.7 Runtime Semantics: KeyedBindingInitialization.
    if (start === undefined || start < 0) {
      start = 0;
    }
    // Return early if start > this.length. Done here to prevent potential uint32
    // coercion fail below.
    if (start > this.length) {
      return ''
    }

    if (end === undefined || end > this.length) {
      end = this.length;
    }

    if (end <= 0) {
      return ''
    }

    // Force coersion to uint32. This will also coerce falsey/NaN values to 0.
    end >>>= 0;
    start >>>= 0;

    if (end <= start) {
      return ''
    }

    if (!encoding) encoding = 'utf8';

    while (true) {
      switch (encoding) {
        case 'hex':
          return hexSlice(this, start, end)

        case 'utf8':
        case 'utf-8':
          return utf8Slice(this, start, end)

        case 'ascii':
          return asciiSlice(this, start, end)

        case 'latin1':
        case 'binary':
          return latin1Slice(this, start, end)

        case 'base64':
          return base64Slice(this, start, end)

        case 'ucs2':
        case 'ucs-2':
        case 'utf16le':
        case 'utf-16le':
          return utf16leSlice(this, start, end)

        default:
          if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
          encoding = (encoding + '').toLowerCase();
          loweredCase = true;
      }
    }
  }

  // The property is used by `Buffer.isBuffer` and `is-buffer` (in Safari 5-7) to detect
  // Buffer instances.
  Buffer.prototype._isBuffer = true;

  function swap (b, n, m) {
    var i = b[n];
    b[n] = b[m];
    b[m] = i;
  }

  Buffer.prototype.swap16 = function swap16 () {
    var len = this.length;
    if (len % 2 !== 0) {
      throw new RangeError('Buffer size must be a multiple of 16-bits')
    }
    for (var i = 0; i < len; i += 2) {
      swap(this, i, i + 1);
    }
    return this
  };

  Buffer.prototype.swap32 = function swap32 () {
    var len = this.length;
    if (len % 4 !== 0) {
      throw new RangeError('Buffer size must be a multiple of 32-bits')
    }
    for (var i = 0; i < len; i += 4) {
      swap(this, i, i + 3);
      swap(this, i + 1, i + 2);
    }
    return this
  };

  Buffer.prototype.swap64 = function swap64 () {
    var len = this.length;
    if (len % 8 !== 0) {
      throw new RangeError('Buffer size must be a multiple of 64-bits')
    }
    for (var i = 0; i < len; i += 8) {
      swap(this, i, i + 7);
      swap(this, i + 1, i + 6);
      swap(this, i + 2, i + 5);
      swap(this, i + 3, i + 4);
    }
    return this
  };

  Buffer.prototype.toString = function toString () {
    var length = this.length | 0;
    if (length === 0) return ''
    if (arguments.length === 0) return utf8Slice(this, 0, length)
    return slowToString.apply(this, arguments)
  };

  Buffer.prototype.equals = function equals (b) {
    if (!internalIsBuffer(b)) throw new TypeError('Argument must be a Buffer')
    if (this === b) return true
    return Buffer.compare(this, b) === 0
  };

  Buffer.prototype.inspect = function inspect () {
    var str = '';
    var max = INSPECT_MAX_BYTES;
    if (this.length > 0) {
      str = this.toString('hex', 0, max).match(/.{2}/g).join(' ');
      if (this.length > max) str += ' ... ';
    }
    return '<Buffer ' + str + '>'
  };

  Buffer.prototype.compare = function compare (target, start, end, thisStart, thisEnd) {
    if (!internalIsBuffer(target)) {
      throw new TypeError('Argument must be a Buffer')
    }

    if (start === undefined) {
      start = 0;
    }
    if (end === undefined) {
      end = target ? target.length : 0;
    }
    if (thisStart === undefined) {
      thisStart = 0;
    }
    if (thisEnd === undefined) {
      thisEnd = this.length;
    }

    if (start < 0 || end > target.length || thisStart < 0 || thisEnd > this.length) {
      throw new RangeError('out of range index')
    }

    if (thisStart >= thisEnd && start >= end) {
      return 0
    }
    if (thisStart >= thisEnd) {
      return -1
    }
    if (start >= end) {
      return 1
    }

    start >>>= 0;
    end >>>= 0;
    thisStart >>>= 0;
    thisEnd >>>= 0;

    if (this === target) return 0

    var x = thisEnd - thisStart;
    var y = end - start;
    var len = Math.min(x, y);

    var thisCopy = this.slice(thisStart, thisEnd);
    var targetCopy = target.slice(start, end);

    for (var i = 0; i < len; ++i) {
      if (thisCopy[i] !== targetCopy[i]) {
        x = thisCopy[i];
        y = targetCopy[i];
        break
      }
    }

    if (x < y) return -1
    if (y < x) return 1
    return 0
  };

  // Finds either the first index of `val` in `buffer` at offset >= `byteOffset`,
  // OR the last index of `val` in `buffer` at offset <= `byteOffset`.
  //
  // Arguments:
  // - buffer - a Buffer to search
  // - val - a string, Buffer, or number
  // - byteOffset - an index into `buffer`; will be clamped to an int32
  // - encoding - an optional encoding, relevant is val is a string
  // - dir - true for indexOf, false for lastIndexOf
  function bidirectionalIndexOf (buffer, val, byteOffset, encoding, dir) {
    // Empty buffer means no match
    if (buffer.length === 0) return -1

    // Normalize byteOffset
    if (typeof byteOffset === 'string') {
      encoding = byteOffset;
      byteOffset = 0;
    } else if (byteOffset > 0x7fffffff) {
      byteOffset = 0x7fffffff;
    } else if (byteOffset < -0x80000000) {
      byteOffset = -0x80000000;
    }
    byteOffset = +byteOffset;  // Coerce to Number.
    if (isNaN(byteOffset)) {
      // byteOffset: it it's undefined, null, NaN, "foo", etc, search whole buffer
      byteOffset = dir ? 0 : (buffer.length - 1);
    }

    // Normalize byteOffset: negative offsets start from the end of the buffer
    if (byteOffset < 0) byteOffset = buffer.length + byteOffset;
    if (byteOffset >= buffer.length) {
      if (dir) return -1
      else byteOffset = buffer.length - 1;
    } else if (byteOffset < 0) {
      if (dir) byteOffset = 0;
      else return -1
    }

    // Normalize val
    if (typeof val === 'string') {
      val = Buffer.from(val, encoding);
    }

    // Finally, search either indexOf (if dir is true) or lastIndexOf
    if (internalIsBuffer(val)) {
      // Special case: looking for empty string/buffer always fails
      if (val.length === 0) {
        return -1
      }
      return arrayIndexOf(buffer, val, byteOffset, encoding, dir)
    } else if (typeof val === 'number') {
      val = val & 0xFF; // Search for a byte value [0-255]
      if (Buffer.TYPED_ARRAY_SUPPORT &&
          typeof Uint8Array.prototype.indexOf === 'function') {
        if (dir) {
          return Uint8Array.prototype.indexOf.call(buffer, val, byteOffset)
        } else {
          return Uint8Array.prototype.lastIndexOf.call(buffer, val, byteOffset)
        }
      }
      return arrayIndexOf(buffer, [ val ], byteOffset, encoding, dir)
    }

    throw new TypeError('val must be string, number or Buffer')
  }

  function arrayIndexOf (arr, val, byteOffset, encoding, dir) {
    var indexSize = 1;
    var arrLength = arr.length;
    var valLength = val.length;

    if (encoding !== undefined) {
      encoding = String(encoding).toLowerCase();
      if (encoding === 'ucs2' || encoding === 'ucs-2' ||
          encoding === 'utf16le' || encoding === 'utf-16le') {
        if (arr.length < 2 || val.length < 2) {
          return -1
        }
        indexSize = 2;
        arrLength /= 2;
        valLength /= 2;
        byteOffset /= 2;
      }
    }

    function read (buf, i) {
      if (indexSize === 1) {
        return buf[i]
      } else {
        return buf.readUInt16BE(i * indexSize)
      }
    }

    var i;
    if (dir) {
      var foundIndex = -1;
      for (i = byteOffset; i < arrLength; i++) {
        if (read(arr, i) === read(val, foundIndex === -1 ? 0 : i - foundIndex)) {
          if (foundIndex === -1) foundIndex = i;
          if (i - foundIndex + 1 === valLength) return foundIndex * indexSize
        } else {
          if (foundIndex !== -1) i -= i - foundIndex;
          foundIndex = -1;
        }
      }
    } else {
      if (byteOffset + valLength > arrLength) byteOffset = arrLength - valLength;
      for (i = byteOffset; i >= 0; i--) {
        var found = true;
        for (var j = 0; j < valLength; j++) {
          if (read(arr, i + j) !== read(val, j)) {
            found = false;
            break
          }
        }
        if (found) return i
      }
    }

    return -1
  }

  Buffer.prototype.includes = function includes (val, byteOffset, encoding) {
    return this.indexOf(val, byteOffset, encoding) !== -1
  };

  Buffer.prototype.indexOf = function indexOf (val, byteOffset, encoding) {
    return bidirectionalIndexOf(this, val, byteOffset, encoding, true)
  };

  Buffer.prototype.lastIndexOf = function lastIndexOf (val, byteOffset, encoding) {
    return bidirectionalIndexOf(this, val, byteOffset, encoding, false)
  };

  function hexWrite (buf, string, offset, length) {
    offset = Number(offset) || 0;
    var remaining = buf.length - offset;
    if (!length) {
      length = remaining;
    } else {
      length = Number(length);
      if (length > remaining) {
        length = remaining;
      }
    }

    // must be an even number of digits
    var strLen = string.length;
    if (strLen % 2 !== 0) throw new TypeError('Invalid hex string')

    if (length > strLen / 2) {
      length = strLen / 2;
    }
    for (var i = 0; i < length; ++i) {
      var parsed = parseInt(string.substr(i * 2, 2), 16);
      if (isNaN(parsed)) return i
      buf[offset + i] = parsed;
    }
    return i
  }

  function utf8Write (buf, string, offset, length) {
    return blitBuffer(utf8ToBytes(string, buf.length - offset), buf, offset, length)
  }

  function asciiWrite (buf, string, offset, length) {
    return blitBuffer(asciiToBytes(string), buf, offset, length)
  }

  function latin1Write (buf, string, offset, length) {
    return asciiWrite(buf, string, offset, length)
  }

  function base64Write (buf, string, offset, length) {
    return blitBuffer(base64ToBytes(string), buf, offset, length)
  }

  function ucs2Write (buf, string, offset, length) {
    return blitBuffer(utf16leToBytes(string, buf.length - offset), buf, offset, length)
  }

  Buffer.prototype.write = function write (string, offset, length, encoding) {
    // Buffer#write(string)
    if (offset === undefined) {
      encoding = 'utf8';
      length = this.length;
      offset = 0;
    // Buffer#write(string, encoding)
    } else if (length === undefined && typeof offset === 'string') {
      encoding = offset;
      length = this.length;
      offset = 0;
    // Buffer#write(string, offset[, length][, encoding])
    } else if (isFinite(offset)) {
      offset = offset | 0;
      if (isFinite(length)) {
        length = length | 0;
        if (encoding === undefined) encoding = 'utf8';
      } else {
        encoding = length;
        length = undefined;
      }
    // legacy write(string, encoding, offset, length) - remove in v0.13
    } else {
      throw new Error(
        'Buffer.write(string, encoding, offset[, length]) is no longer supported'
      )
    }

    var remaining = this.length - offset;
    if (length === undefined || length > remaining) length = remaining;

    if ((string.length > 0 && (length < 0 || offset < 0)) || offset > this.length) {
      throw new RangeError('Attempt to write outside buffer bounds')
    }

    if (!encoding) encoding = 'utf8';

    var loweredCase = false;
    for (;;) {
      switch (encoding) {
        case 'hex':
          return hexWrite(this, string, offset, length)

        case 'utf8':
        case 'utf-8':
          return utf8Write(this, string, offset, length)

        case 'ascii':
          return asciiWrite(this, string, offset, length)

        case 'latin1':
        case 'binary':
          return latin1Write(this, string, offset, length)

        case 'base64':
          // Warning: maxLength not taken into account in base64Write
          return base64Write(this, string, offset, length)

        case 'ucs2':
        case 'ucs-2':
        case 'utf16le':
        case 'utf-16le':
          return ucs2Write(this, string, offset, length)

        default:
          if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
          encoding = ('' + encoding).toLowerCase();
          loweredCase = true;
      }
    }
  };

  Buffer.prototype.toJSON = function toJSON () {
    return {
      type: 'Buffer',
      data: Array.prototype.slice.call(this._arr || this, 0)
    }
  };

  function base64Slice (buf, start, end) {
    if (start === 0 && end === buf.length) {
      return fromByteArray(buf)
    } else {
      return fromByteArray(buf.slice(start, end))
    }
  }

  function utf8Slice (buf, start, end) {
    end = Math.min(buf.length, end);
    var res = [];

    var i = start;
    while (i < end) {
      var firstByte = buf[i];
      var codePoint = null;
      var bytesPerSequence = (firstByte > 0xEF) ? 4
        : (firstByte > 0xDF) ? 3
        : (firstByte > 0xBF) ? 2
        : 1;

      if (i + bytesPerSequence <= end) {
        var secondByte, thirdByte, fourthByte, tempCodePoint;

        switch (bytesPerSequence) {
          case 1:
            if (firstByte < 0x80) {
              codePoint = firstByte;
            }
            break
          case 2:
            secondByte = buf[i + 1];
            if ((secondByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0x1F) << 0x6 | (secondByte & 0x3F);
              if (tempCodePoint > 0x7F) {
                codePoint = tempCodePoint;
              }
            }
            break
          case 3:
            secondByte = buf[i + 1];
            thirdByte = buf[i + 2];
            if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0xF) << 0xC | (secondByte & 0x3F) << 0x6 | (thirdByte & 0x3F);
              if (tempCodePoint > 0x7FF && (tempCodePoint < 0xD800 || tempCodePoint > 0xDFFF)) {
                codePoint = tempCodePoint;
              }
            }
            break
          case 4:
            secondByte = buf[i + 1];
            thirdByte = buf[i + 2];
            fourthByte = buf[i + 3];
            if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80 && (fourthByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0xF) << 0x12 | (secondByte & 0x3F) << 0xC | (thirdByte & 0x3F) << 0x6 | (fourthByte & 0x3F);
              if (tempCodePoint > 0xFFFF && tempCodePoint < 0x110000) {
                codePoint = tempCodePoint;
              }
            }
        }
      }

      if (codePoint === null) {
        // we did not generate a valid codePoint so insert a
        // replacement char (U+FFFD) and advance only 1 byte
        codePoint = 0xFFFD;
        bytesPerSequence = 1;
      } else if (codePoint > 0xFFFF) {
        // encode to utf16 (surrogate pair dance)
        codePoint -= 0x10000;
        res.push(codePoint >>> 10 & 0x3FF | 0xD800);
        codePoint = 0xDC00 | codePoint & 0x3FF;
      }

      res.push(codePoint);
      i += bytesPerSequence;
    }

    return decodeCodePointsArray(res)
  }

  // Based on http://stackoverflow.com/a/22747272/680742, the browser with
  // the lowest limit is Chrome, with 0x10000 args.
  // We go 1 magnitude less, for safety
  var MAX_ARGUMENTS_LENGTH = 0x1000;

  function decodeCodePointsArray (codePoints) {
    var len = codePoints.length;
    if (len <= MAX_ARGUMENTS_LENGTH) {
      return String.fromCharCode.apply(String, codePoints) // avoid extra slice()
    }

    // Decode in chunks to avoid "call stack size exceeded".
    var res = '';
    var i = 0;
    while (i < len) {
      res += String.fromCharCode.apply(
        String,
        codePoints.slice(i, i += MAX_ARGUMENTS_LENGTH)
      );
    }
    return res
  }

  function asciiSlice (buf, start, end) {
    var ret = '';
    end = Math.min(buf.length, end);

    for (var i = start; i < end; ++i) {
      ret += String.fromCharCode(buf[i] & 0x7F);
    }
    return ret
  }

  function latin1Slice (buf, start, end) {
    var ret = '';
    end = Math.min(buf.length, end);

    for (var i = start; i < end; ++i) {
      ret += String.fromCharCode(buf[i]);
    }
    return ret
  }

  function hexSlice (buf, start, end) {
    var len = buf.length;

    if (!start || start < 0) start = 0;
    if (!end || end < 0 || end > len) end = len;

    var out = '';
    for (var i = start; i < end; ++i) {
      out += toHex(buf[i]);
    }
    return out
  }

  function utf16leSlice (buf, start, end) {
    var bytes = buf.slice(start, end);
    var res = '';
    for (var i = 0; i < bytes.length; i += 2) {
      res += String.fromCharCode(bytes[i] + bytes[i + 1] * 256);
    }
    return res
  }

  Buffer.prototype.slice = function slice (start, end) {
    var len = this.length;
    start = ~~start;
    end = end === undefined ? len : ~~end;

    if (start < 0) {
      start += len;
      if (start < 0) start = 0;
    } else if (start > len) {
      start = len;
    }

    if (end < 0) {
      end += len;
      if (end < 0) end = 0;
    } else if (end > len) {
      end = len;
    }

    if (end < start) end = start;

    var newBuf;
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      newBuf = this.subarray(start, end);
      newBuf.__proto__ = Buffer.prototype;
    } else {
      var sliceLen = end - start;
      newBuf = new Buffer(sliceLen, undefined);
      for (var i = 0; i < sliceLen; ++i) {
        newBuf[i] = this[i + start];
      }
    }

    return newBuf
  };

  /*
   * Need to make sure that buffer isn't trying to write out of bounds.
   */
  function checkOffset (offset, ext, length) {
    if ((offset % 1) !== 0 || offset < 0) throw new RangeError('offset is not uint')
    if (offset + ext > length) throw new RangeError('Trying to access beyond buffer length')
  }

  Buffer.prototype.readUIntLE = function readUIntLE (offset, byteLength, noAssert) {
    offset = offset | 0;
    byteLength = byteLength | 0;
    if (!noAssert) checkOffset(offset, byteLength, this.length);

    var val = this[offset];
    var mul = 1;
    var i = 0;
    while (++i < byteLength && (mul *= 0x100)) {
      val += this[offset + i] * mul;
    }

    return val
  };

  Buffer.prototype.readUIntBE = function readUIntBE (offset, byteLength, noAssert) {
    offset = offset | 0;
    byteLength = byteLength | 0;
    if (!noAssert) {
      checkOffset(offset, byteLength, this.length);
    }

    var val = this[offset + --byteLength];
    var mul = 1;
    while (byteLength > 0 && (mul *= 0x100)) {
      val += this[offset + --byteLength] * mul;
    }

    return val
  };

  Buffer.prototype.readUInt8 = function readUInt8 (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 1, this.length);
    return this[offset]
  };

  Buffer.prototype.readUInt16LE = function readUInt16LE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 2, this.length);
    return this[offset] | (this[offset + 1] << 8)
  };

  Buffer.prototype.readUInt16BE = function readUInt16BE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 2, this.length);
    return (this[offset] << 8) | this[offset + 1]
  };

  Buffer.prototype.readUInt32LE = function readUInt32LE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 4, this.length);

    return ((this[offset]) |
        (this[offset + 1] << 8) |
        (this[offset + 2] << 16)) +
        (this[offset + 3] * 0x1000000)
  };

  Buffer.prototype.readUInt32BE = function readUInt32BE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 4, this.length);

    return (this[offset] * 0x1000000) +
      ((this[offset + 1] << 16) |
      (this[offset + 2] << 8) |
      this[offset + 3])
  };

  Buffer.prototype.readIntLE = function readIntLE (offset, byteLength, noAssert) {
    offset = offset | 0;
    byteLength = byteLength | 0;
    if (!noAssert) checkOffset(offset, byteLength, this.length);

    var val = this[offset];
    var mul = 1;
    var i = 0;
    while (++i < byteLength && (mul *= 0x100)) {
      val += this[offset + i] * mul;
    }
    mul *= 0x80;

    if (val >= mul) val -= Math.pow(2, 8 * byteLength);

    return val
  };

  Buffer.prototype.readIntBE = function readIntBE (offset, byteLength, noAssert) {
    offset = offset | 0;
    byteLength = byteLength | 0;
    if (!noAssert) checkOffset(offset, byteLength, this.length);

    var i = byteLength;
    var mul = 1;
    var val = this[offset + --i];
    while (i > 0 && (mul *= 0x100)) {
      val += this[offset + --i] * mul;
    }
    mul *= 0x80;

    if (val >= mul) val -= Math.pow(2, 8 * byteLength);

    return val
  };

  Buffer.prototype.readInt8 = function readInt8 (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 1, this.length);
    if (!(this[offset] & 0x80)) return (this[offset])
    return ((0xff - this[offset] + 1) * -1)
  };

  Buffer.prototype.readInt16LE = function readInt16LE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 2, this.length);
    var val = this[offset] | (this[offset + 1] << 8);
    return (val & 0x8000) ? val | 0xFFFF0000 : val
  };

  Buffer.prototype.readInt16BE = function readInt16BE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 2, this.length);
    var val = this[offset + 1] | (this[offset] << 8);
    return (val & 0x8000) ? val | 0xFFFF0000 : val
  };

  Buffer.prototype.readInt32LE = function readInt32LE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 4, this.length);

    return (this[offset]) |
      (this[offset + 1] << 8) |
      (this[offset + 2] << 16) |
      (this[offset + 3] << 24)
  };

  Buffer.prototype.readInt32BE = function readInt32BE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 4, this.length);

    return (this[offset] << 24) |
      (this[offset + 1] << 16) |
      (this[offset + 2] << 8) |
      (this[offset + 3])
  };

  Buffer.prototype.readFloatLE = function readFloatLE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 4, this.length);
    return read(this, offset, true, 23, 4)
  };

  Buffer.prototype.readFloatBE = function readFloatBE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 4, this.length);
    return read(this, offset, false, 23, 4)
  };

  Buffer.prototype.readDoubleLE = function readDoubleLE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 8, this.length);
    return read(this, offset, true, 52, 8)
  };

  Buffer.prototype.readDoubleBE = function readDoubleBE (offset, noAssert) {
    if (!noAssert) checkOffset(offset, 8, this.length);
    return read(this, offset, false, 52, 8)
  };

  function checkInt (buf, value, offset, ext, max, min) {
    if (!internalIsBuffer(buf)) throw new TypeError('"buffer" argument must be a Buffer instance')
    if (value > max || value < min) throw new RangeError('"value" argument is out of bounds')
    if (offset + ext > buf.length) throw new RangeError('Index out of range')
  }

  Buffer.prototype.writeUIntLE = function writeUIntLE (value, offset, byteLength, noAssert) {
    value = +value;
    offset = offset | 0;
    byteLength = byteLength | 0;
    if (!noAssert) {
      var maxBytes = Math.pow(2, 8 * byteLength) - 1;
      checkInt(this, value, offset, byteLength, maxBytes, 0);
    }

    var mul = 1;
    var i = 0;
    this[offset] = value & 0xFF;
    while (++i < byteLength && (mul *= 0x100)) {
      this[offset + i] = (value / mul) & 0xFF;
    }

    return offset + byteLength
  };

  Buffer.prototype.writeUIntBE = function writeUIntBE (value, offset, byteLength, noAssert) {
    value = +value;
    offset = offset | 0;
    byteLength = byteLength | 0;
    if (!noAssert) {
      var maxBytes = Math.pow(2, 8 * byteLength) - 1;
      checkInt(this, value, offset, byteLength, maxBytes, 0);
    }

    var i = byteLength - 1;
    var mul = 1;
    this[offset + i] = value & 0xFF;
    while (--i >= 0 && (mul *= 0x100)) {
      this[offset + i] = (value / mul) & 0xFF;
    }

    return offset + byteLength
  };

  Buffer.prototype.writeUInt8 = function writeUInt8 (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 1, 0xff, 0);
    if (!Buffer.TYPED_ARRAY_SUPPORT) value = Math.floor(value);
    this[offset] = (value & 0xff);
    return offset + 1
  };

  function objectWriteUInt16 (buf, value, offset, littleEndian) {
    if (value < 0) value = 0xffff + value + 1;
    for (var i = 0, j = Math.min(buf.length - offset, 2); i < j; ++i) {
      buf[offset + i] = (value & (0xff << (8 * (littleEndian ? i : 1 - i)))) >>>
        (littleEndian ? i : 1 - i) * 8;
    }
  }

  Buffer.prototype.writeUInt16LE = function writeUInt16LE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0);
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset] = (value & 0xff);
      this[offset + 1] = (value >>> 8);
    } else {
      objectWriteUInt16(this, value, offset, true);
    }
    return offset + 2
  };

  Buffer.prototype.writeUInt16BE = function writeUInt16BE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0);
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset] = (value >>> 8);
      this[offset + 1] = (value & 0xff);
    } else {
      objectWriteUInt16(this, value, offset, false);
    }
    return offset + 2
  };

  function objectWriteUInt32 (buf, value, offset, littleEndian) {
    if (value < 0) value = 0xffffffff + value + 1;
    for (var i = 0, j = Math.min(buf.length - offset, 4); i < j; ++i) {
      buf[offset + i] = (value >>> (littleEndian ? i : 3 - i) * 8) & 0xff;
    }
  }

  Buffer.prototype.writeUInt32LE = function writeUInt32LE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0);
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset + 3] = (value >>> 24);
      this[offset + 2] = (value >>> 16);
      this[offset + 1] = (value >>> 8);
      this[offset] = (value & 0xff);
    } else {
      objectWriteUInt32(this, value, offset, true);
    }
    return offset + 4
  };

  Buffer.prototype.writeUInt32BE = function writeUInt32BE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0);
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset] = (value >>> 24);
      this[offset + 1] = (value >>> 16);
      this[offset + 2] = (value >>> 8);
      this[offset + 3] = (value & 0xff);
    } else {
      objectWriteUInt32(this, value, offset, false);
    }
    return offset + 4
  };

  Buffer.prototype.writeIntLE = function writeIntLE (value, offset, byteLength, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) {
      var limit = Math.pow(2, 8 * byteLength - 1);

      checkInt(this, value, offset, byteLength, limit - 1, -limit);
    }

    var i = 0;
    var mul = 1;
    var sub = 0;
    this[offset] = value & 0xFF;
    while (++i < byteLength && (mul *= 0x100)) {
      if (value < 0 && sub === 0 && this[offset + i - 1] !== 0) {
        sub = 1;
      }
      this[offset + i] = ((value / mul) >> 0) - sub & 0xFF;
    }

    return offset + byteLength
  };

  Buffer.prototype.writeIntBE = function writeIntBE (value, offset, byteLength, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) {
      var limit = Math.pow(2, 8 * byteLength - 1);

      checkInt(this, value, offset, byteLength, limit - 1, -limit);
    }

    var i = byteLength - 1;
    var mul = 1;
    var sub = 0;
    this[offset + i] = value & 0xFF;
    while (--i >= 0 && (mul *= 0x100)) {
      if (value < 0 && sub === 0 && this[offset + i + 1] !== 0) {
        sub = 1;
      }
      this[offset + i] = ((value / mul) >> 0) - sub & 0xFF;
    }

    return offset + byteLength
  };

  Buffer.prototype.writeInt8 = function writeInt8 (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 1, 0x7f, -0x80);
    if (!Buffer.TYPED_ARRAY_SUPPORT) value = Math.floor(value);
    if (value < 0) value = 0xff + value + 1;
    this[offset] = (value & 0xff);
    return offset + 1
  };

  Buffer.prototype.writeInt16LE = function writeInt16LE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000);
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset] = (value & 0xff);
      this[offset + 1] = (value >>> 8);
    } else {
      objectWriteUInt16(this, value, offset, true);
    }
    return offset + 2
  };

  Buffer.prototype.writeInt16BE = function writeInt16BE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000);
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset] = (value >>> 8);
      this[offset + 1] = (value & 0xff);
    } else {
      objectWriteUInt16(this, value, offset, false);
    }
    return offset + 2
  };

  Buffer.prototype.writeInt32LE = function writeInt32LE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000);
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset] = (value & 0xff);
      this[offset + 1] = (value >>> 8);
      this[offset + 2] = (value >>> 16);
      this[offset + 3] = (value >>> 24);
    } else {
      objectWriteUInt32(this, value, offset, true);
    }
    return offset + 4
  };

  Buffer.prototype.writeInt32BE = function writeInt32BE (value, offset, noAssert) {
    value = +value;
    offset = offset | 0;
    if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000);
    if (value < 0) value = 0xffffffff + value + 1;
    if (Buffer.TYPED_ARRAY_SUPPORT) {
      this[offset] = (value >>> 24);
      this[offset + 1] = (value >>> 16);
      this[offset + 2] = (value >>> 8);
      this[offset + 3] = (value & 0xff);
    } else {
      objectWriteUInt32(this, value, offset, false);
    }
    return offset + 4
  };

  function checkIEEE754 (buf, value, offset, ext, max, min) {
    if (offset + ext > buf.length) throw new RangeError('Index out of range')
    if (offset < 0) throw new RangeError('Index out of range')
  }

  function writeFloat (buf, value, offset, littleEndian, noAssert) {
    if (!noAssert) {
      checkIEEE754(buf, value, offset, 4);
    }
    write(buf, value, offset, littleEndian, 23, 4);
    return offset + 4
  }

  Buffer.prototype.writeFloatLE = function writeFloatLE (value, offset, noAssert) {
    return writeFloat(this, value, offset, true, noAssert)
  };

  Buffer.prototype.writeFloatBE = function writeFloatBE (value, offset, noAssert) {
    return writeFloat(this, value, offset, false, noAssert)
  };

  function writeDouble (buf, value, offset, littleEndian, noAssert) {
    if (!noAssert) {
      checkIEEE754(buf, value, offset, 8);
    }
    write(buf, value, offset, littleEndian, 52, 8);
    return offset + 8
  }

  Buffer.prototype.writeDoubleLE = function writeDoubleLE (value, offset, noAssert) {
    return writeDouble(this, value, offset, true, noAssert)
  };

  Buffer.prototype.writeDoubleBE = function writeDoubleBE (value, offset, noAssert) {
    return writeDouble(this, value, offset, false, noAssert)
  };

  // copy(targetBuffer, targetStart=0, sourceStart=0, sourceEnd=buffer.length)
  Buffer.prototype.copy = function copy (target, targetStart, start, end) {
    if (!start) start = 0;
    if (!end && end !== 0) end = this.length;
    if (targetStart >= target.length) targetStart = target.length;
    if (!targetStart) targetStart = 0;
    if (end > 0 && end < start) end = start;

    // Copy 0 bytes; we're done
    if (end === start) return 0
    if (target.length === 0 || this.length === 0) return 0

    // Fatal error conditions
    if (targetStart < 0) {
      throw new RangeError('targetStart out of bounds')
    }
    if (start < 0 || start >= this.length) throw new RangeError('sourceStart out of bounds')
    if (end < 0) throw new RangeError('sourceEnd out of bounds')

    // Are we oob?
    if (end > this.length) end = this.length;
    if (target.length - targetStart < end - start) {
      end = target.length - targetStart + start;
    }

    var len = end - start;
    var i;

    if (this === target && start < targetStart && targetStart < end) {
      // descending copy from end
      for (i = len - 1; i >= 0; --i) {
        target[i + targetStart] = this[i + start];
      }
    } else if (len < 1000 || !Buffer.TYPED_ARRAY_SUPPORT) {
      // ascending copy from start
      for (i = 0; i < len; ++i) {
        target[i + targetStart] = this[i + start];
      }
    } else {
      Uint8Array.prototype.set.call(
        target,
        this.subarray(start, start + len),
        targetStart
      );
    }

    return len
  };

  // Usage:
  //    buffer.fill(number[, offset[, end]])
  //    buffer.fill(buffer[, offset[, end]])
  //    buffer.fill(string[, offset[, end]][, encoding])
  Buffer.prototype.fill = function fill (val, start, end, encoding) {
    // Handle string cases:
    if (typeof val === 'string') {
      if (typeof start === 'string') {
        encoding = start;
        start = 0;
        end = this.length;
      } else if (typeof end === 'string') {
        encoding = end;
        end = this.length;
      }
      if (val.length === 1) {
        var code = val.charCodeAt(0);
        if (code < 256) {
          val = code;
        }
      }
      if (encoding !== undefined && typeof encoding !== 'string') {
        throw new TypeError('encoding must be a string')
      }
      if (typeof encoding === 'string' && !Buffer.isEncoding(encoding)) {
        throw new TypeError('Unknown encoding: ' + encoding)
      }
    } else if (typeof val === 'number') {
      val = val & 255;
    }

    // Invalid ranges are not set to a default, so can range check early.
    if (start < 0 || this.length < start || this.length < end) {
      throw new RangeError('Out of range index')
    }

    if (end <= start) {
      return this
    }

    start = start >>> 0;
    end = end === undefined ? this.length : end >>> 0;

    if (!val) val = 0;

    var i;
    if (typeof val === 'number') {
      for (i = start; i < end; ++i) {
        this[i] = val;
      }
    } else {
      var bytes = internalIsBuffer(val)
        ? val
        : utf8ToBytes(new Buffer(val, encoding).toString());
      var len = bytes.length;
      for (i = 0; i < end - start; ++i) {
        this[i + start] = bytes[i % len];
      }
    }

    return this
  };

  // HELPER FUNCTIONS
  // ================

  var INVALID_BASE64_RE = /[^+\/0-9A-Za-z-_]/g;

  function base64clean (str) {
    // Node strips out invalid characters like \n and \t from the string, base64-js does not
    str = stringtrim(str).replace(INVALID_BASE64_RE, '');
    // Node converts strings with length < 2 to ''
    if (str.length < 2) return ''
    // Node allows for non-padded base64 strings (missing trailing ===), base64-js does not
    while (str.length % 4 !== 0) {
      str = str + '=';
    }
    return str
  }

  function stringtrim (str) {
    if (str.trim) return str.trim()
    return str.replace(/^\s+|\s+$/g, '')
  }

  function toHex (n) {
    if (n < 16) return '0' + n.toString(16)
    return n.toString(16)
  }

  function utf8ToBytes (string, units) {
    units = units || Infinity;
    var codePoint;
    var length = string.length;
    var leadSurrogate = null;
    var bytes = [];

    for (var i = 0; i < length; ++i) {
      codePoint = string.charCodeAt(i);

      // is surrogate component
      if (codePoint > 0xD7FF && codePoint < 0xE000) {
        // last char was a lead
        if (!leadSurrogate) {
          // no lead yet
          if (codePoint > 0xDBFF) {
            // unexpected trail
            if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD);
            continue
          } else if (i + 1 === length) {
            // unpaired lead
            if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD);
            continue
          }

          // valid lead
          leadSurrogate = codePoint;

          continue
        }

        // 2 leads in a row
        if (codePoint < 0xDC00) {
          if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD);
          leadSurrogate = codePoint;
          continue
        }

        // valid surrogate pair
        codePoint = (leadSurrogate - 0xD800 << 10 | codePoint - 0xDC00) + 0x10000;
      } else if (leadSurrogate) {
        // valid bmp char, but last char was a lead
        if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD);
      }

      leadSurrogate = null;

      // encode utf8
      if (codePoint < 0x80) {
        if ((units -= 1) < 0) break
        bytes.push(codePoint);
      } else if (codePoint < 0x800) {
        if ((units -= 2) < 0) break
        bytes.push(
          codePoint >> 0x6 | 0xC0,
          codePoint & 0x3F | 0x80
        );
      } else if (codePoint < 0x10000) {
        if ((units -= 3) < 0) break
        bytes.push(
          codePoint >> 0xC | 0xE0,
          codePoint >> 0x6 & 0x3F | 0x80,
          codePoint & 0x3F | 0x80
        );
      } else if (codePoint < 0x110000) {
        if ((units -= 4) < 0) break
        bytes.push(
          codePoint >> 0x12 | 0xF0,
          codePoint >> 0xC & 0x3F | 0x80,
          codePoint >> 0x6 & 0x3F | 0x80,
          codePoint & 0x3F | 0x80
        );
      } else {
        throw new Error('Invalid code point')
      }
    }

    return bytes
  }

  function asciiToBytes (str) {
    var byteArray = [];
    for (var i = 0; i < str.length; ++i) {
      // Node's code seems to be doing this and not & 0x7F..
      byteArray.push(str.charCodeAt(i) & 0xFF);
    }
    return byteArray
  }

  function utf16leToBytes (str, units) {
    var c, hi, lo;
    var byteArray = [];
    for (var i = 0; i < str.length; ++i) {
      if ((units -= 2) < 0) break

      c = str.charCodeAt(i);
      hi = c >> 8;
      lo = c % 256;
      byteArray.push(lo);
      byteArray.push(hi);
    }

    return byteArray
  }


  function base64ToBytes (str) {
    return toByteArray(base64clean(str))
  }

  function blitBuffer (src, dst, offset, length) {
    for (var i = 0; i < length; ++i) {
      if ((i + offset >= dst.length) || (i >= src.length)) break
      dst[i + offset] = src[i];
    }
    return i
  }

  function isnan (val) {
    return val !== val // eslint-disable-line no-self-compare
  }


  // the following is from is-buffer, also by Feross Aboukhadijeh and with same lisence
  // The _isBuffer check is for Safari 5-7 support, because it's missing
  // Object.prototype.constructor. Remove this eventually
  function isBuffer(obj) {
    return obj != null && (!!obj._isBuffer || isFastBuffer(obj) || isSlowBuffer(obj))
  }

  function isFastBuffer (obj) {
    return !!obj.constructor && typeof obj.constructor.isBuffer === 'function' && obj.constructor.isBuffer(obj)
  }

  // For Node v0.10 support. Remove this eventually.
  function isSlowBuffer (obj) {
    return typeof obj.readFloatLE === 'function' && typeof obj.slice === 'function' && isFastBuffer(obj.slice(0, 0))
  }

  // shim for using process in browser
  // based off https://github.com/defunctzombie/node-process/blob/master/browser.js

  function defaultSetTimout() {
      throw new Error('setTimeout has not been defined');
  }
  function defaultClearTimeout () {
      throw new Error('clearTimeout has not been defined');
  }
  var cachedSetTimeout = defaultSetTimout;
  var cachedClearTimeout = defaultClearTimeout;
  if (typeof global$1.setTimeout === 'function') {
      cachedSetTimeout = setTimeout;
  }
  if (typeof global$1.clearTimeout === 'function') {
      cachedClearTimeout = clearTimeout;
  }

  function runTimeout(fun) {
      if (cachedSetTimeout === setTimeout) {
          //normal enviroments in sane situations
          return setTimeout(fun, 0);
      }
      // if setTimeout wasn't available but was latter defined
      if ((cachedSetTimeout === defaultSetTimout || !cachedSetTimeout) && setTimeout) {
          cachedSetTimeout = setTimeout;
          return setTimeout(fun, 0);
      }
      try {
          // when when somebody has screwed with setTimeout but no I.E. maddness
          return cachedSetTimeout(fun, 0);
      } catch(e){
          try {
              // When we are in I.E. but the script has been evaled so I.E. doesn't trust the global object when called normally
              return cachedSetTimeout.call(null, fun, 0);
          } catch(e){
              // same as above but when it's a version of I.E. that must have the global object for 'this', hopfully our context correct otherwise it will throw a global error
              return cachedSetTimeout.call(this, fun, 0);
          }
      }


  }
  function runClearTimeout(marker) {
      if (cachedClearTimeout === clearTimeout) {
          //normal enviroments in sane situations
          return clearTimeout(marker);
      }
      // if clearTimeout wasn't available but was latter defined
      if ((cachedClearTimeout === defaultClearTimeout || !cachedClearTimeout) && clearTimeout) {
          cachedClearTimeout = clearTimeout;
          return clearTimeout(marker);
      }
      try {
          // when when somebody has screwed with setTimeout but no I.E. maddness
          return cachedClearTimeout(marker);
      } catch (e){
          try {
              // When we are in I.E. but the script has been evaled so I.E. doesn't  trust the global object when called normally
              return cachedClearTimeout.call(null, marker);
          } catch (e){
              // same as above but when it's a version of I.E. that must have the global object for 'this', hopfully our context correct otherwise it will throw a global error.
              // Some versions of I.E. have different rules for clearTimeout vs setTimeout
              return cachedClearTimeout.call(this, marker);
          }
      }



  }
  var queue = [];
  var draining = false;
  var currentQueue;
  var queueIndex = -1;

  function cleanUpNextTick() {
      if (!draining || !currentQueue) {
          return;
      }
      draining = false;
      if (currentQueue.length) {
          queue = currentQueue.concat(queue);
      } else {
          queueIndex = -1;
      }
      if (queue.length) {
          drainQueue();
      }
  }

  function drainQueue() {
      if (draining) {
          return;
      }
      var timeout = runTimeout(cleanUpNextTick);
      draining = true;

      var len = queue.length;
      while(len) {
          currentQueue = queue;
          queue = [];
          while (++queueIndex < len) {
              if (currentQueue) {
                  currentQueue[queueIndex].run();
              }
          }
          queueIndex = -1;
          len = queue.length;
      }
      currentQueue = null;
      draining = false;
      runClearTimeout(timeout);
  }
  function nextTick(fun) {
      var args = new Array(arguments.length - 1);
      if (arguments.length > 1) {
          for (var i = 1; i < arguments.length; i++) {
              args[i - 1] = arguments[i];
          }
      }
      queue.push(new Item(fun, args));
      if (queue.length === 1 && !draining) {
          runTimeout(drainQueue);
      }
  }
  // v8 likes predictible objects
  function Item(fun, array) {
      this.fun = fun;
      this.array = array;
  }
  Item.prototype.run = function () {
      this.fun.apply(null, this.array);
  };
  var title = 'browser';
  var platform = 'browser';
  var browser = true;
  var env = {};
  var argv = [];
  var version = ''; // empty string to avoid regexp issues
  var versions = {};
  var release = {};
  var config = {};

  function noop() {}

  var on = noop;
  var addListener = noop;
  var once = noop;
  var off = noop;
  var removeListener = noop;
  var removeAllListeners = noop;
  var emit = noop;

  function binding(name) {
      throw new Error('process.binding is not supported');
  }

  function cwd () { return '/' }
  function chdir (dir) {
      throw new Error('process.chdir is not supported');
  }function umask() { return 0; }

  // from https://github.com/kumavis/browser-process-hrtime/blob/master/index.js
  var performance = global$1.performance || {};
  var performanceNow =
    performance.now        ||
    performance.mozNow     ||
    performance.msNow      ||
    performance.oNow       ||
    performance.webkitNow  ||
    function(){ return (new Date()).getTime() };

  // generate timestamp or delta
  // see http://nodejs.org/api/process.html#process_process_hrtime
  function hrtime(previousTimestamp){
    var clocktime = performanceNow.call(performance)*1e-3;
    var seconds = Math.floor(clocktime);
    var nanoseconds = Math.floor((clocktime%1)*1e9);
    if (previousTimestamp) {
      seconds = seconds - previousTimestamp[0];
      nanoseconds = nanoseconds - previousTimestamp[1];
      if (nanoseconds<0) {
        seconds--;
        nanoseconds += 1e9;
      }
    }
    return [seconds,nanoseconds]
  }

  var startTime = new Date();
  function uptime() {
    var currentTime = new Date();
    var dif = currentTime - startTime;
    return dif / 1000;
  }

  var process = {
    nextTick: nextTick,
    title: title,
    browser: browser,
    env: env,
    argv: argv,
    version: version,
    versions: versions,
    on: on,
    addListener: addListener,
    once: once,
    off: off,
    removeListener: removeListener,
    removeAllListeners: removeAllListeners,
    emit: emit,
    binding: binding,
    cwd: cwd,
    chdir: chdir,
    umask: umask,
    hrtime: hrtime,
    platform: platform,
    release: release,
    config: config,
    uptime: uptime
  };

  var inherits;
  if (typeof Object.create === 'function'){
    inherits = function inherits(ctor, superCtor) {
      // implementation from standard node.js 'util' module
      ctor.super_ = superCtor;
      ctor.prototype = Object.create(superCtor.prototype, {
        constructor: {
          value: ctor,
          enumerable: false,
          writable: true,
          configurable: true
        }
      });
    };
  } else {
    inherits = function inherits(ctor, superCtor) {
      ctor.super_ = superCtor;
      var TempCtor = function () {};
      TempCtor.prototype = superCtor.prototype;
      ctor.prototype = new TempCtor();
      ctor.prototype.constructor = ctor;
    };
  }
  var inherits$1 = inherits;

  var formatRegExp = /%[sdj%]/g;
  function format(f) {
    if (!isString(f)) {
      var objects = [];
      for (var i = 0; i < arguments.length; i++) {
        objects.push(inspect(arguments[i]));
      }
      return objects.join(' ');
    }

    var i = 1;
    var args = arguments;
    var len = args.length;
    var str = String(f).replace(formatRegExp, function(x) {
      if (x === '%%') return '%';
      if (i >= len) return x;
      switch (x) {
        case '%s': return String(args[i++]);
        case '%d': return Number(args[i++]);
        case '%j':
          try {
            return JSON.stringify(args[i++]);
          } catch (_) {
            return '[Circular]';
          }
        default:
          return x;
      }
    });
    for (var x = args[i]; i < len; x = args[++i]) {
      if (isNull(x) || !isObject(x)) {
        str += ' ' + x;
      } else {
        str += ' ' + inspect(x);
      }
    }
    return str;
  }

  // Mark that a method should not be used.
  // Returns a modified function which warns once by default.
  // If --no-deprecation is set, then it is a no-op.
  function deprecate(fn, msg) {
    // Allow for deprecating things in the process of starting up.
    if (isUndefined(global$1.process)) {
      return function() {
        return deprecate(fn, msg).apply(this, arguments);
      };
    }

    if (process.noDeprecation === true) {
      return fn;
    }

    var warned = false;
    function deprecated() {
      if (!warned) {
        if (process.throwDeprecation) {
          throw new Error(msg);
        } else if (process.traceDeprecation) {
          console.trace(msg);
        } else {
          console.error(msg);
        }
        warned = true;
      }
      return fn.apply(this, arguments);
    }

    return deprecated;
  }

  var debugs = {};
  var debugEnviron;
  function debuglog(set) {
    if (isUndefined(debugEnviron))
      debugEnviron = process.env.NODE_DEBUG || '';
    set = set.toUpperCase();
    if (!debugs[set]) {
      if (new RegExp('\\b' + set + '\\b', 'i').test(debugEnviron)) {
        var pid = 0;
        debugs[set] = function() {
          var msg = format.apply(null, arguments);
          console.error('%s %d: %s', set, pid, msg);
        };
      } else {
        debugs[set] = function() {};
      }
    }
    return debugs[set];
  }

  /**
   * Echos the value of a value. Trys to print the value out
   * in the best way possible given the different types.
   *
   * @param {Object} obj The object to print out.
   * @param {Object} opts Optional options object that alters the output.
   */
  /* legacy: obj, showHidden, depth, colors*/
  function inspect(obj, opts) {
    // default options
    var ctx = {
      seen: [],
      stylize: stylizeNoColor
    };
    // legacy...
    if (arguments.length >= 3) ctx.depth = arguments[2];
    if (arguments.length >= 4) ctx.colors = arguments[3];
    if (isBoolean(opts)) {
      // legacy...
      ctx.showHidden = opts;
    } else if (opts) {
      // got an "options" object
      _extend(ctx, opts);
    }
    // set default options
    if (isUndefined(ctx.showHidden)) ctx.showHidden = false;
    if (isUndefined(ctx.depth)) ctx.depth = 2;
    if (isUndefined(ctx.colors)) ctx.colors = false;
    if (isUndefined(ctx.customInspect)) ctx.customInspect = true;
    if (ctx.colors) ctx.stylize = stylizeWithColor;
    return formatValue(ctx, obj, ctx.depth);
  }

  // http://en.wikipedia.org/wiki/ANSI_escape_code#graphics
  inspect.colors = {
    'bold' : [1, 22],
    'italic' : [3, 23],
    'underline' : [4, 24],
    'inverse' : [7, 27],
    'white' : [37, 39],
    'grey' : [90, 39],
    'black' : [30, 39],
    'blue' : [34, 39],
    'cyan' : [36, 39],
    'green' : [32, 39],
    'magenta' : [35, 39],
    'red' : [31, 39],
    'yellow' : [33, 39]
  };

  // Don't use 'blue' not visible on cmd.exe
  inspect.styles = {
    'special': 'cyan',
    'number': 'yellow',
    'boolean': 'yellow',
    'undefined': 'grey',
    'null': 'bold',
    'string': 'green',
    'date': 'magenta',
    // "name": intentionally not styling
    'regexp': 'red'
  };


  function stylizeWithColor(str, styleType) {
    var style = inspect.styles[styleType];

    if (style) {
      return '\u001b[' + inspect.colors[style][0] + 'm' + str +
             '\u001b[' + inspect.colors[style][1] + 'm';
    } else {
      return str;
    }
  }


  function stylizeNoColor(str, styleType) {
    return str;
  }


  function arrayToHash(array) {
    var hash = {};

    array.forEach(function(val, idx) {
      hash[val] = true;
    });

    return hash;
  }


  function formatValue(ctx, value, recurseTimes) {
    // Provide a hook for user-specified inspect functions.
    // Check that value is an object with an inspect function on it
    if (ctx.customInspect &&
        value &&
        isFunction(value.inspect) &&
        // Filter out the util module, it's inspect function is special
        value.inspect !== inspect &&
        // Also filter out any prototype objects using the circular check.
        !(value.constructor && value.constructor.prototype === value)) {
      var ret = value.inspect(recurseTimes, ctx);
      if (!isString(ret)) {
        ret = formatValue(ctx, ret, recurseTimes);
      }
      return ret;
    }

    // Primitive types cannot have properties
    var primitive = formatPrimitive(ctx, value);
    if (primitive) {
      return primitive;
    }

    // Look up the keys of the object.
    var keys = Object.keys(value);
    var visibleKeys = arrayToHash(keys);

    if (ctx.showHidden) {
      keys = Object.getOwnPropertyNames(value);
    }

    // IE doesn't make error fields non-enumerable
    // http://msdn.microsoft.com/en-us/library/ie/dww52sbt(v=vs.94).aspx
    if (isError(value)
        && (keys.indexOf('message') >= 0 || keys.indexOf('description') >= 0)) {
      return formatError(value);
    }

    // Some type of object without properties can be shortcutted.
    if (keys.length === 0) {
      if (isFunction(value)) {
        var name = value.name ? ': ' + value.name : '';
        return ctx.stylize('[Function' + name + ']', 'special');
      }
      if (isRegExp(value)) {
        return ctx.stylize(RegExp.prototype.toString.call(value), 'regexp');
      }
      if (isDate(value)) {
        return ctx.stylize(Date.prototype.toString.call(value), 'date');
      }
      if (isError(value)) {
        return formatError(value);
      }
    }

    var base = '', array = false, braces = ['{', '}'];

    // Make Array say that they are Array
    if (isArray(value)) {
      array = true;
      braces = ['[', ']'];
    }

    // Make functions say that they are functions
    if (isFunction(value)) {
      var n = value.name ? ': ' + value.name : '';
      base = ' [Function' + n + ']';
    }

    // Make RegExps say that they are RegExps
    if (isRegExp(value)) {
      base = ' ' + RegExp.prototype.toString.call(value);
    }

    // Make dates with properties first say the date
    if (isDate(value)) {
      base = ' ' + Date.prototype.toUTCString.call(value);
    }

    // Make error with message first say the error
    if (isError(value)) {
      base = ' ' + formatError(value);
    }

    if (keys.length === 0 && (!array || value.length == 0)) {
      return braces[0] + base + braces[1];
    }

    if (recurseTimes < 0) {
      if (isRegExp(value)) {
        return ctx.stylize(RegExp.prototype.toString.call(value), 'regexp');
      } else {
        return ctx.stylize('[Object]', 'special');
      }
    }

    ctx.seen.push(value);

    var output;
    if (array) {
      output = formatArray(ctx, value, recurseTimes, visibleKeys, keys);
    } else {
      output = keys.map(function(key) {
        return formatProperty(ctx, value, recurseTimes, visibleKeys, key, array);
      });
    }

    ctx.seen.pop();

    return reduceToSingleString(output, base, braces);
  }


  function formatPrimitive(ctx, value) {
    if (isUndefined(value))
      return ctx.stylize('undefined', 'undefined');
    if (isString(value)) {
      var simple = '\'' + JSON.stringify(value).replace(/^"|"$/g, '')
                                               .replace(/'/g, "\\'")
                                               .replace(/\\"/g, '"') + '\'';
      return ctx.stylize(simple, 'string');
    }
    if (isNumber(value))
      return ctx.stylize('' + value, 'number');
    if (isBoolean(value))
      return ctx.stylize('' + value, 'boolean');
    // For some reason typeof null is "object", so special case here.
    if (isNull(value))
      return ctx.stylize('null', 'null');
  }


  function formatError(value) {
    return '[' + Error.prototype.toString.call(value) + ']';
  }


  function formatArray(ctx, value, recurseTimes, visibleKeys, keys) {
    var output = [];
    for (var i = 0, l = value.length; i < l; ++i) {
      if (hasOwnProperty(value, String(i))) {
        output.push(formatProperty(ctx, value, recurseTimes, visibleKeys,
            String(i), true));
      } else {
        output.push('');
      }
    }
    keys.forEach(function(key) {
      if (!key.match(/^\d+$/)) {
        output.push(formatProperty(ctx, value, recurseTimes, visibleKeys,
            key, true));
      }
    });
    return output;
  }


  function formatProperty(ctx, value, recurseTimes, visibleKeys, key, array) {
    var name, str, desc;
    desc = Object.getOwnPropertyDescriptor(value, key) || { value: value[key] };
    if (desc.get) {
      if (desc.set) {
        str = ctx.stylize('[Getter/Setter]', 'special');
      } else {
        str = ctx.stylize('[Getter]', 'special');
      }
    } else {
      if (desc.set) {
        str = ctx.stylize('[Setter]', 'special');
      }
    }
    if (!hasOwnProperty(visibleKeys, key)) {
      name = '[' + key + ']';
    }
    if (!str) {
      if (ctx.seen.indexOf(desc.value) < 0) {
        if (isNull(recurseTimes)) {
          str = formatValue(ctx, desc.value, null);
        } else {
          str = formatValue(ctx, desc.value, recurseTimes - 1);
        }
        if (str.indexOf('\n') > -1) {
          if (array) {
            str = str.split('\n').map(function(line) {
              return '  ' + line;
            }).join('\n').substr(2);
          } else {
            str = '\n' + str.split('\n').map(function(line) {
              return '   ' + line;
            }).join('\n');
          }
        }
      } else {
        str = ctx.stylize('[Circular]', 'special');
      }
    }
    if (isUndefined(name)) {
      if (array && key.match(/^\d+$/)) {
        return str;
      }
      name = JSON.stringify('' + key);
      if (name.match(/^"([a-zA-Z_][a-zA-Z_0-9]*)"$/)) {
        name = name.substr(1, name.length - 2);
        name = ctx.stylize(name, 'name');
      } else {
        name = name.replace(/'/g, "\\'")
                   .replace(/\\"/g, '"')
                   .replace(/(^"|"$)/g, "'");
        name = ctx.stylize(name, 'string');
      }
    }

    return name + ': ' + str;
  }


  function reduceToSingleString(output, base, braces) {
    var length = output.reduce(function(prev, cur) {
      if (cur.indexOf('\n') >= 0) ;
      return prev + cur.replace(/\u001b\[\d\d?m/g, '').length + 1;
    }, 0);

    if (length > 60) {
      return braces[0] +
             (base === '' ? '' : base + '\n ') +
             ' ' +
             output.join(',\n  ') +
             ' ' +
             braces[1];
    }

    return braces[0] + base + ' ' + output.join(', ') + ' ' + braces[1];
  }


  // NOTE: These type checking functions intentionally don't use `instanceof`
  // because it is fragile and can be easily faked with `Object.create()`.
  function isArray(ar) {
    return Array.isArray(ar);
  }

  function isBoolean(arg) {
    return typeof arg === 'boolean';
  }

  function isNull(arg) {
    return arg === null;
  }

  function isNumber(arg) {
    return typeof arg === 'number';
  }

  function isString(arg) {
    return typeof arg === 'string';
  }

  function isUndefined(arg) {
    return arg === void 0;
  }

  function isRegExp(re) {
    return isObject(re) && objectToString(re) === '[object RegExp]';
  }

  function isObject(arg) {
    return typeof arg === 'object' && arg !== null;
  }

  function isDate(d) {
    return isObject(d) && objectToString(d) === '[object Date]';
  }

  function isError(e) {
    return isObject(e) &&
        (objectToString(e) === '[object Error]' || e instanceof Error);
  }

  function isFunction(arg) {
    return typeof arg === 'function';
  }

  function objectToString(o) {
    return Object.prototype.toString.call(o);
  }

  function _extend(origin, add) {
    // Don't do anything if add isn't an object
    if (!add || !isObject(add)) return origin;

    var keys = Object.keys(add);
    var i = keys.length;
    while (i--) {
      origin[keys[i]] = add[keys[i]];
    }
    return origin;
  }
  function hasOwnProperty(obj, prop) {
    return Object.prototype.hasOwnProperty.call(obj, prop);
  }

  function BufferList() {
    this.head = null;
    this.tail = null;
    this.length = 0;
  }

  BufferList.prototype.push = function (v) {
    var entry = { data: v, next: null };
    if (this.length > 0) this.tail.next = entry;else this.head = entry;
    this.tail = entry;
    ++this.length;
  };

  BufferList.prototype.unshift = function (v) {
    var entry = { data: v, next: this.head };
    if (this.length === 0) this.tail = entry;
    this.head = entry;
    ++this.length;
  };

  BufferList.prototype.shift = function () {
    if (this.length === 0) return;
    var ret = this.head.data;
    if (this.length === 1) this.head = this.tail = null;else this.head = this.head.next;
    --this.length;
    return ret;
  };

  BufferList.prototype.clear = function () {
    this.head = this.tail = null;
    this.length = 0;
  };

  BufferList.prototype.join = function (s) {
    if (this.length === 0) return '';
    var p = this.head;
    var ret = '' + p.data;
    while (p = p.next) {
      ret += s + p.data;
    }return ret;
  };

  BufferList.prototype.concat = function (n) {
    if (this.length === 0) return Buffer.alloc(0);
    if (this.length === 1) return this.head.data;
    var ret = Buffer.allocUnsafe(n >>> 0);
    var p = this.head;
    var i = 0;
    while (p) {
      p.data.copy(ret, i);
      i += p.data.length;
      p = p.next;
    }
    return ret;
  };

  // Copyright Joyent, Inc. and other Node contributors.
  var isBufferEncoding = Buffer.isEncoding
    || function(encoding) {
         switch (encoding && encoding.toLowerCase()) {
           case 'hex': case 'utf8': case 'utf-8': case 'ascii': case 'binary': case 'base64': case 'ucs2': case 'ucs-2': case 'utf16le': case 'utf-16le': case 'raw': return true;
           default: return false;
         }
       };


  function assertEncoding(encoding) {
    if (encoding && !isBufferEncoding(encoding)) {
      throw new Error('Unknown encoding: ' + encoding);
    }
  }

  // StringDecoder provides an interface for efficiently splitting a series of
  // buffers into a series of JS strings without breaking apart multi-byte
  // characters. CESU-8 is handled as part of the UTF-8 encoding.
  //
  // @TODO Handling all encodings inside a single object makes it very difficult
  // to reason about this code, so it should be split up in the future.
  // @TODO There should be a utf8-strict encoding that rejects invalid UTF-8 code
  // points as used by CESU-8.
  function StringDecoder(encoding) {
    this.encoding = (encoding || 'utf8').toLowerCase().replace(/[-_]/, '');
    assertEncoding(encoding);
    switch (this.encoding) {
      case 'utf8':
        // CESU-8 represents each of Surrogate Pair by 3-bytes
        this.surrogateSize = 3;
        break;
      case 'ucs2':
      case 'utf16le':
        // UTF-16 represents each of Surrogate Pair by 2-bytes
        this.surrogateSize = 2;
        this.detectIncompleteChar = utf16DetectIncompleteChar;
        break;
      case 'base64':
        // Base-64 stores 3 bytes in 4 chars, and pads the remainder.
        this.surrogateSize = 3;
        this.detectIncompleteChar = base64DetectIncompleteChar;
        break;
      default:
        this.write = passThroughWrite;
        return;
    }

    // Enough space to store all bytes of a single character. UTF-8 needs 4
    // bytes, but CESU-8 may require up to 6 (3 bytes per surrogate).
    this.charBuffer = new Buffer(6);
    // Number of bytes received for the current incomplete multi-byte character.
    this.charReceived = 0;
    // Number of bytes expected for the current incomplete multi-byte character.
    this.charLength = 0;
  }

  // write decodes the given buffer and returns it as JS string that is
  // guaranteed to not contain any partial multi-byte characters. Any partial
  // character found at the end of the buffer is buffered up, and will be
  // returned when calling write again with the remaining bytes.
  //
  // Note: Converting a Buffer containing an orphan surrogate to a String
  // currently works, but converting a String to a Buffer (via `new Buffer`, or
  // Buffer#write) will replace incomplete surrogates with the unicode
  // replacement character. See https://codereview.chromium.org/121173009/ .
  StringDecoder.prototype.write = function(buffer) {
    var charStr = '';
    // if our last write ended with an incomplete multibyte character
    while (this.charLength) {
      // determine how many remaining bytes this buffer has to offer for this char
      var available = (buffer.length >= this.charLength - this.charReceived) ?
          this.charLength - this.charReceived :
          buffer.length;

      // add the new bytes to the char buffer
      buffer.copy(this.charBuffer, this.charReceived, 0, available);
      this.charReceived += available;

      if (this.charReceived < this.charLength) {
        // still not enough chars in this buffer? wait for more ...
        return '';
      }

      // remove bytes belonging to the current character from the buffer
      buffer = buffer.slice(available, buffer.length);

      // get the character that was split
      charStr = this.charBuffer.slice(0, this.charLength).toString(this.encoding);

      // CESU-8: lead surrogate (D800-DBFF) is also the incomplete character
      var charCode = charStr.charCodeAt(charStr.length - 1);
      if (charCode >= 0xD800 && charCode <= 0xDBFF) {
        this.charLength += this.surrogateSize;
        charStr = '';
        continue;
      }
      this.charReceived = this.charLength = 0;

      // if there are no more bytes in this buffer, just emit our char
      if (buffer.length === 0) {
        return charStr;
      }
      break;
    }

    // determine and set charLength / charReceived
    this.detectIncompleteChar(buffer);

    var end = buffer.length;
    if (this.charLength) {
      // buffer the incomplete character bytes we got
      buffer.copy(this.charBuffer, 0, buffer.length - this.charReceived, end);
      end -= this.charReceived;
    }

    charStr += buffer.toString(this.encoding, 0, end);

    var end = charStr.length - 1;
    var charCode = charStr.charCodeAt(end);
    // CESU-8: lead surrogate (D800-DBFF) is also the incomplete character
    if (charCode >= 0xD800 && charCode <= 0xDBFF) {
      var size = this.surrogateSize;
      this.charLength += size;
      this.charReceived += size;
      this.charBuffer.copy(this.charBuffer, size, 0, size);
      buffer.copy(this.charBuffer, 0, 0, size);
      return charStr.substring(0, end);
    }

    // or just emit the charStr
    return charStr;
  };

  // detectIncompleteChar determines if there is an incomplete UTF-8 character at
  // the end of the given buffer. If so, it sets this.charLength to the byte
  // length that character, and sets this.charReceived to the number of bytes
  // that are available for this character.
  StringDecoder.prototype.detectIncompleteChar = function(buffer) {
    // determine how many bytes we have to check at the end of this buffer
    var i = (buffer.length >= 3) ? 3 : buffer.length;

    // Figure out if one of the last i bytes of our buffer announces an
    // incomplete char.
    for (; i > 0; i--) {
      var c = buffer[buffer.length - i];

      // See http://en.wikipedia.org/wiki/UTF-8#Description

      // 110XXXXX
      if (i == 1 && c >> 5 == 0x06) {
        this.charLength = 2;
        break;
      }

      // 1110XXXX
      if (i <= 2 && c >> 4 == 0x0E) {
        this.charLength = 3;
        break;
      }

      // 11110XXX
      if (i <= 3 && c >> 3 == 0x1E) {
        this.charLength = 4;
        break;
      }
    }
    this.charReceived = i;
  };

  StringDecoder.prototype.end = function(buffer) {
    var res = '';
    if (buffer && buffer.length)
      res = this.write(buffer);

    if (this.charReceived) {
      var cr = this.charReceived;
      var buf = this.charBuffer;
      var enc = this.encoding;
      res += buf.slice(0, cr).toString(enc);
    }

    return res;
  };

  function passThroughWrite(buffer) {
    return buffer.toString(this.encoding);
  }

  function utf16DetectIncompleteChar(buffer) {
    this.charReceived = buffer.length % 2;
    this.charLength = this.charReceived ? 2 : 0;
  }

  function base64DetectIncompleteChar(buffer) {
    this.charReceived = buffer.length % 3;
    this.charLength = this.charReceived ? 3 : 0;
  }

  Readable.ReadableState = ReadableState;

  var debug = debuglog('stream');
  inherits$1(Readable, EventEmitter);

  function prependListener(emitter, event, fn) {
    // Sadly this is not cacheable as some libraries bundle their own
    // event emitter implementation with them.
    if (typeof emitter.prependListener === 'function') {
      return emitter.prependListener(event, fn);
    } else {
      // This is a hack to make sure that our error handler is attached before any
      // userland ones.  NEVER DO THIS. This is here only because this code needs
      // to continue to work with older versions of Node.js that do not include
      // the prependListener() method. The goal is to eventually remove this hack.
      if (!emitter._events || !emitter._events[event])
        emitter.on(event, fn);
      else if (Array.isArray(emitter._events[event]))
        emitter._events[event].unshift(fn);
      else
        emitter._events[event] = [fn, emitter._events[event]];
    }
  }
  function listenerCount (emitter, type) {
    return emitter.listeners(type).length;
  }
  function ReadableState(options, stream) {

    options = options || {};

    // object stream flag. Used to make read(n) ignore n and to
    // make all the buffer merging and length checks go away
    this.objectMode = !!options.objectMode;

    if (stream instanceof Duplex) this.objectMode = this.objectMode || !!options.readableObjectMode;

    // the point at which it stops calling _read() to fill the buffer
    // Note: 0 is a valid value, means "don't call _read preemptively ever"
    var hwm = options.highWaterMark;
    var defaultHwm = this.objectMode ? 16 : 16 * 1024;
    this.highWaterMark = hwm || hwm === 0 ? hwm : defaultHwm;

    // cast to ints.
    this.highWaterMark = ~ ~this.highWaterMark;

    // A linked list is used to store data chunks instead of an array because the
    // linked list can remove elements from the beginning faster than
    // array.shift()
    this.buffer = new BufferList();
    this.length = 0;
    this.pipes = null;
    this.pipesCount = 0;
    this.flowing = null;
    this.ended = false;
    this.endEmitted = false;
    this.reading = false;

    // a flag to be able to tell if the onwrite cb is called immediately,
    // or on a later tick.  We set this to true at first, because any
    // actions that shouldn't happen until "later" should generally also
    // not happen before the first write call.
    this.sync = true;

    // whenever we return null, then we set a flag to say
    // that we're awaiting a 'readable' event emission.
    this.needReadable = false;
    this.emittedReadable = false;
    this.readableListening = false;
    this.resumeScheduled = false;

    // Crypto is kind of old and crusty.  Historically, its default string
    // encoding is 'binary' so we have to make this configurable.
    // Everything else in the universe uses 'utf8', though.
    this.defaultEncoding = options.defaultEncoding || 'utf8';

    // when piping, we only care about 'readable' events that happen
    // after read()ing all the bytes and not getting any pushback.
    this.ranOut = false;

    // the number of writers that are awaiting a drain event in .pipe()s
    this.awaitDrain = 0;

    // if true, a maybeReadMore has been scheduled
    this.readingMore = false;

    this.decoder = null;
    this.encoding = null;
    if (options.encoding) {
      this.decoder = new StringDecoder(options.encoding);
      this.encoding = options.encoding;
    }
  }
  function Readable(options) {

    if (!(this instanceof Readable)) return new Readable(options);

    this._readableState = new ReadableState(options, this);

    // legacy
    this.readable = true;

    if (options && typeof options.read === 'function') this._read = options.read;

    EventEmitter.call(this);
  }

  // Manually shove something into the read() buffer.
  // This returns true if the highWaterMark has not been hit yet,
  // similar to how Writable.write() returns true if you should
  // write() some more.
  Readable.prototype.push = function (chunk, encoding) {
    var state = this._readableState;

    if (!state.objectMode && typeof chunk === 'string') {
      encoding = encoding || state.defaultEncoding;
      if (encoding !== state.encoding) {
        chunk = Buffer.from(chunk, encoding);
        encoding = '';
      }
    }

    return readableAddChunk(this, state, chunk, encoding, false);
  };

  // Unshift should *always* be something directly out of read()
  Readable.prototype.unshift = function (chunk) {
    var state = this._readableState;
    return readableAddChunk(this, state, chunk, '', true);
  };

  Readable.prototype.isPaused = function () {
    return this._readableState.flowing === false;
  };

  function readableAddChunk(stream, state, chunk, encoding, addToFront) {
    var er = chunkInvalid(state, chunk);
    if (er) {
      stream.emit('error', er);
    } else if (chunk === null) {
      state.reading = false;
      onEofChunk(stream, state);
    } else if (state.objectMode || chunk && chunk.length > 0) {
      if (state.ended && !addToFront) {
        var e = new Error('stream.push() after EOF');
        stream.emit('error', e);
      } else if (state.endEmitted && addToFront) {
        var _e = new Error('stream.unshift() after end event');
        stream.emit('error', _e);
      } else {
        var skipAdd;
        if (state.decoder && !addToFront && !encoding) {
          chunk = state.decoder.write(chunk);
          skipAdd = !state.objectMode && chunk.length === 0;
        }

        if (!addToFront) state.reading = false;

        // Don't add to the buffer if we've decoded to an empty string chunk and
        // we're not in object mode
        if (!skipAdd) {
          // if we want the data now, just emit it.
          if (state.flowing && state.length === 0 && !state.sync) {
            stream.emit('data', chunk);
            stream.read(0);
          } else {
            // update the buffer info.
            state.length += state.objectMode ? 1 : chunk.length;
            if (addToFront) state.buffer.unshift(chunk);else state.buffer.push(chunk);

            if (state.needReadable) emitReadable(stream);
          }
        }

        maybeReadMore(stream, state);
      }
    } else if (!addToFront) {
      state.reading = false;
    }

    return needMoreData(state);
  }

  // if it's past the high water mark, we can push in some more.
  // Also, if we have no data yet, we can stand some
  // more bytes.  This is to work around cases where hwm=0,
  // such as the repl.  Also, if the push() triggered a
  // readable event, and the user called read(largeNumber) such that
  // needReadable was set, then we ought to push more, so that another
  // 'readable' event will be triggered.
  function needMoreData(state) {
    return !state.ended && (state.needReadable || state.length < state.highWaterMark || state.length === 0);
  }

  // backwards compatibility.
  Readable.prototype.setEncoding = function (enc) {
    this._readableState.decoder = new StringDecoder(enc);
    this._readableState.encoding = enc;
    return this;
  };

  // Don't raise the hwm > 8MB
  var MAX_HWM = 0x800000;
  function computeNewHighWaterMark(n) {
    if (n >= MAX_HWM) {
      n = MAX_HWM;
    } else {
      // Get the next highest power of 2 to prevent increasing hwm excessively in
      // tiny amounts
      n--;
      n |= n >>> 1;
      n |= n >>> 2;
      n |= n >>> 4;
      n |= n >>> 8;
      n |= n >>> 16;
      n++;
    }
    return n;
  }

  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function howMuchToRead(n, state) {
    if (n <= 0 || state.length === 0 && state.ended) return 0;
    if (state.objectMode) return 1;
    if (n !== n) {
      // Only flow one buffer at a time
      if (state.flowing && state.length) return state.buffer.head.data.length;else return state.length;
    }
    // If we're asking for more than the current hwm, then raise the hwm.
    if (n > state.highWaterMark) state.highWaterMark = computeNewHighWaterMark(n);
    if (n <= state.length) return n;
    // Don't have enough
    if (!state.ended) {
      state.needReadable = true;
      return 0;
    }
    return state.length;
  }

  // you can override either this method, or the async _read(n) below.
  Readable.prototype.read = function (n) {
    debug('read', n);
    n = parseInt(n, 10);
    var state = this._readableState;
    var nOrig = n;

    if (n !== 0) state.emittedReadable = false;

    // if we're doing read(0) to trigger a readable event, but we
    // already have a bunch of data in the buffer, then just trigger
    // the 'readable' event and move on.
    if (n === 0 && state.needReadable && (state.length >= state.highWaterMark || state.ended)) {
      debug('read: emitReadable', state.length, state.ended);
      if (state.length === 0 && state.ended) endReadable(this);else emitReadable(this);
      return null;
    }

    n = howMuchToRead(n, state);

    // if we've ended, and we're now clear, then finish it up.
    if (n === 0 && state.ended) {
      if (state.length === 0) endReadable(this);
      return null;
    }

    // All the actual chunk generation logic needs to be
    // *below* the call to _read.  The reason is that in certain
    // synthetic stream cases, such as passthrough streams, _read
    // may be a completely synchronous operation which may change
    // the state of the read buffer, providing enough data when
    // before there was *not* enough.
    //
    // So, the steps are:
    // 1. Figure out what the state of things will be after we do
    // a read from the buffer.
    //
    // 2. If that resulting state will trigger a _read, then call _read.
    // Note that this may be asynchronous, or synchronous.  Yes, it is
    // deeply ugly to write APIs this way, but that still doesn't mean
    // that the Readable class should behave improperly, as streams are
    // designed to be sync/async agnostic.
    // Take note if the _read call is sync or async (ie, if the read call
    // has returned yet), so that we know whether or not it's safe to emit
    // 'readable' etc.
    //
    // 3. Actually pull the requested chunks out of the buffer and return.

    // if we need a readable event, then we need to do some reading.
    var doRead = state.needReadable;
    debug('need readable', doRead);

    // if we currently have less than the highWaterMark, then also read some
    if (state.length === 0 || state.length - n < state.highWaterMark) {
      doRead = true;
      debug('length less than watermark', doRead);
    }

    // however, if we've ended, then there's no point, and if we're already
    // reading, then it's unnecessary.
    if (state.ended || state.reading) {
      doRead = false;
      debug('reading or ended', doRead);
    } else if (doRead) {
      debug('do read');
      state.reading = true;
      state.sync = true;
      // if the length is currently zero, then we *need* a readable event.
      if (state.length === 0) state.needReadable = true;
      // call internal read method
      this._read(state.highWaterMark);
      state.sync = false;
      // If _read pushed data synchronously, then `reading` will be false,
      // and we need to re-evaluate how much data we can return to the user.
      if (!state.reading) n = howMuchToRead(nOrig, state);
    }

    var ret;
    if (n > 0) ret = fromList(n, state);else ret = null;

    if (ret === null) {
      state.needReadable = true;
      n = 0;
    } else {
      state.length -= n;
    }

    if (state.length === 0) {
      // If we have nothing in the buffer, then we want to know
      // as soon as we *do* get something into the buffer.
      if (!state.ended) state.needReadable = true;

      // If we tried to read() past the EOF, then emit end on the next tick.
      if (nOrig !== n && state.ended) endReadable(this);
    }

    if (ret !== null) this.emit('data', ret);

    return ret;
  };

  function chunkInvalid(state, chunk) {
    var er = null;
    if (!isBuffer(chunk) && typeof chunk !== 'string' && chunk !== null && chunk !== undefined && !state.objectMode) {
      er = new TypeError('Invalid non-string/buffer chunk');
    }
    return er;
  }

  function onEofChunk(stream, state) {
    if (state.ended) return;
    if (state.decoder) {
      var chunk = state.decoder.end();
      if (chunk && chunk.length) {
        state.buffer.push(chunk);
        state.length += state.objectMode ? 1 : chunk.length;
      }
    }
    state.ended = true;

    // emit 'readable' now to make sure it gets picked up.
    emitReadable(stream);
  }

  // Don't emit readable right away in sync mode, because this can trigger
  // another read() call => stack overflow.  This way, it might trigger
  // a nextTick recursion warning, but that's not so bad.
  function emitReadable(stream) {
    var state = stream._readableState;
    state.needReadable = false;
    if (!state.emittedReadable) {
      debug('emitReadable', state.flowing);
      state.emittedReadable = true;
      if (state.sync) nextTick(emitReadable_, stream);else emitReadable_(stream);
    }
  }

  function emitReadable_(stream) {
    debug('emit readable');
    stream.emit('readable');
    flow(stream);
  }

  // at this point, the user has presumably seen the 'readable' event,
  // and called read() to consume some data.  that may have triggered
  // in turn another _read(n) call, in which case reading = true if
  // it's in progress.
  // However, if we're not ended, or reading, and the length < hwm,
  // then go ahead and try to read some more preemptively.
  function maybeReadMore(stream, state) {
    if (!state.readingMore) {
      state.readingMore = true;
      nextTick(maybeReadMore_, stream, state);
    }
  }

  function maybeReadMore_(stream, state) {
    var len = state.length;
    while (!state.reading && !state.flowing && !state.ended && state.length < state.highWaterMark) {
      debug('maybeReadMore read 0');
      stream.read(0);
      if (len === state.length)
        // didn't get any data, stop spinning.
        break;else len = state.length;
    }
    state.readingMore = false;
  }

  // abstract method.  to be overridden in specific implementation classes.
  // call cb(er, data) where data is <= n in length.
  // for virtual (non-string, non-buffer) streams, "length" is somewhat
  // arbitrary, and perhaps not very meaningful.
  Readable.prototype._read = function (n) {
    this.emit('error', new Error('not implemented'));
  };

  Readable.prototype.pipe = function (dest, pipeOpts) {
    var src = this;
    var state = this._readableState;

    switch (state.pipesCount) {
      case 0:
        state.pipes = dest;
        break;
      case 1:
        state.pipes = [state.pipes, dest];
        break;
      default:
        state.pipes.push(dest);
        break;
    }
    state.pipesCount += 1;
    debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts);

    var doEnd = (!pipeOpts || pipeOpts.end !== false);

    var endFn = doEnd ? onend : cleanup;
    if (state.endEmitted) nextTick(endFn);else src.once('end', endFn);

    dest.on('unpipe', onunpipe);
    function onunpipe(readable) {
      debug('onunpipe');
      if (readable === src) {
        cleanup();
      }
    }

    function onend() {
      debug('onend');
      dest.end();
    }

    // when the dest drains, it reduces the awaitDrain counter
    // on the source.  This would be more elegant with a .once()
    // handler in flow(), but adding and removing repeatedly is
    // too slow.
    var ondrain = pipeOnDrain(src);
    dest.on('drain', ondrain);

    var cleanedUp = false;
    function cleanup() {
      debug('cleanup');
      // cleanup event handlers once the pipe is broken
      dest.removeListener('close', onclose);
      dest.removeListener('finish', onfinish);
      dest.removeListener('drain', ondrain);
      dest.removeListener('error', onerror);
      dest.removeListener('unpipe', onunpipe);
      src.removeListener('end', onend);
      src.removeListener('end', cleanup);
      src.removeListener('data', ondata);

      cleanedUp = true;

      // if the reader is waiting for a drain event from this
      // specific writer, then it would cause it to never start
      // flowing again.
      // So, if this is awaiting a drain, then we just call it now.
      // If we don't know, then assume that we are waiting for one.
      if (state.awaitDrain && (!dest._writableState || dest._writableState.needDrain)) ondrain();
    }

    // If the user pushes more data while we're writing to dest then we'll end up
    // in ondata again. However, we only want to increase awaitDrain once because
    // dest will only emit one 'drain' event for the multiple writes.
    // => Introduce a guard on increasing awaitDrain.
    var increasedAwaitDrain = false;
    src.on('data', ondata);
    function ondata(chunk) {
      debug('ondata');
      increasedAwaitDrain = false;
      var ret = dest.write(chunk);
      if (false === ret && !increasedAwaitDrain) {
        // If the user unpiped during `dest.write()`, it is possible
        // to get stuck in a permanently paused state if that write
        // also returned false.
        // => Check whether `dest` is still a piping destination.
        if ((state.pipesCount === 1 && state.pipes === dest || state.pipesCount > 1 && indexOf(state.pipes, dest) !== -1) && !cleanedUp) {
          debug('false write response, pause', src._readableState.awaitDrain);
          src._readableState.awaitDrain++;
          increasedAwaitDrain = true;
        }
        src.pause();
      }
    }

    // if the dest has an error, then stop piping into it.
    // however, don't suppress the throwing behavior for this.
    function onerror(er) {
      debug('onerror', er);
      unpipe();
      dest.removeListener('error', onerror);
      if (listenerCount(dest, 'error') === 0) dest.emit('error', er);
    }

    // Make sure our error handler is attached before userland ones.
    prependListener(dest, 'error', onerror);

    // Both close and finish should trigger unpipe, but only once.
    function onclose() {
      dest.removeListener('finish', onfinish);
      unpipe();
    }
    dest.once('close', onclose);
    function onfinish() {
      debug('onfinish');
      dest.removeListener('close', onclose);
      unpipe();
    }
    dest.once('finish', onfinish);

    function unpipe() {
      debug('unpipe');
      src.unpipe(dest);
    }

    // tell the dest that it's being piped to
    dest.emit('pipe', src);

    // start the flow if it hasn't been started already.
    if (!state.flowing) {
      debug('pipe resume');
      src.resume();
    }

    return dest;
  };

  function pipeOnDrain(src) {
    return function () {
      var state = src._readableState;
      debug('pipeOnDrain', state.awaitDrain);
      if (state.awaitDrain) state.awaitDrain--;
      if (state.awaitDrain === 0 && src.listeners('data').length) {
        state.flowing = true;
        flow(src);
      }
    };
  }

  Readable.prototype.unpipe = function (dest) {
    var state = this._readableState;

    // if we're not piping anywhere, then do nothing.
    if (state.pipesCount === 0) return this;

    // just one destination.  most common case.
    if (state.pipesCount === 1) {
      // passed in one, but it's not the right one.
      if (dest && dest !== state.pipes) return this;

      if (!dest) dest = state.pipes;

      // got a match.
      state.pipes = null;
      state.pipesCount = 0;
      state.flowing = false;
      if (dest) dest.emit('unpipe', this);
      return this;
    }

    // slow case. multiple pipe destinations.

    if (!dest) {
      // remove all.
      var dests = state.pipes;
      var len = state.pipesCount;
      state.pipes = null;
      state.pipesCount = 0;
      state.flowing = false;

      for (var _i = 0; _i < len; _i++) {
        dests[_i].emit('unpipe', this);
      }return this;
    }

    // try to find the right one.
    var i = indexOf(state.pipes, dest);
    if (i === -1) return this;

    state.pipes.splice(i, 1);
    state.pipesCount -= 1;
    if (state.pipesCount === 1) state.pipes = state.pipes[0];

    dest.emit('unpipe', this);

    return this;
  };

  // set up data events if they are asked for
  // Ensure readable listeners eventually get something
  Readable.prototype.on = function (ev, fn) {
    var res = EventEmitter.prototype.on.call(this, ev, fn);

    if (ev === 'data') {
      // Start flowing on next tick if stream isn't explicitly paused
      if (this._readableState.flowing !== false) this.resume();
    } else if (ev === 'readable') {
      var state = this._readableState;
      if (!state.endEmitted && !state.readableListening) {
        state.readableListening = state.needReadable = true;
        state.emittedReadable = false;
        if (!state.reading) {
          nextTick(nReadingNextTick, this);
        } else if (state.length) {
          emitReadable(this);
        }
      }
    }

    return res;
  };
  Readable.prototype.addListener = Readable.prototype.on;

  function nReadingNextTick(self) {
    debug('readable nexttick read 0');
    self.read(0);
  }

  // pause() and resume() are remnants of the legacy readable stream API
  // If the user uses them, then switch into old mode.
  Readable.prototype.resume = function () {
    var state = this._readableState;
    if (!state.flowing) {
      debug('resume');
      state.flowing = true;
      resume(this, state);
    }
    return this;
  };

  function resume(stream, state) {
    if (!state.resumeScheduled) {
      state.resumeScheduled = true;
      nextTick(resume_, stream, state);
    }
  }

  function resume_(stream, state) {
    if (!state.reading) {
      debug('resume read 0');
      stream.read(0);
    }

    state.resumeScheduled = false;
    state.awaitDrain = 0;
    stream.emit('resume');
    flow(stream);
    if (state.flowing && !state.reading) stream.read(0);
  }

  Readable.prototype.pause = function () {
    debug('call pause flowing=%j', this._readableState.flowing);
    if (false !== this._readableState.flowing) {
      debug('pause');
      this._readableState.flowing = false;
      this.emit('pause');
    }
    return this;
  };

  function flow(stream) {
    var state = stream._readableState;
    debug('flow', state.flowing);
    while (state.flowing && stream.read() !== null) {}
  }

  // wrap an old-style stream as the async data source.
  // This is *not* part of the readable stream interface.
  // It is an ugly unfortunate mess of history.
  Readable.prototype.wrap = function (stream) {
    var state = this._readableState;
    var paused = false;

    var self = this;
    stream.on('end', function () {
      debug('wrapped end');
      if (state.decoder && !state.ended) {
        var chunk = state.decoder.end();
        if (chunk && chunk.length) self.push(chunk);
      }

      self.push(null);
    });

    stream.on('data', function (chunk) {
      debug('wrapped data');
      if (state.decoder) chunk = state.decoder.write(chunk);

      // don't skip over falsy values in objectMode
      if (state.objectMode && (chunk === null || chunk === undefined)) return;else if (!state.objectMode && (!chunk || !chunk.length)) return;

      var ret = self.push(chunk);
      if (!ret) {
        paused = true;
        stream.pause();
      }
    });

    // proxy all the other methods.
    // important when wrapping filters and duplexes.
    for (var i in stream) {
      if (this[i] === undefined && typeof stream[i] === 'function') {
        this[i] = function (method) {
          return function () {
            return stream[method].apply(stream, arguments);
          };
        }(i);
      }
    }

    // proxy certain important events.
    var events = ['error', 'close', 'destroy', 'pause', 'resume'];
    forEach(events, function (ev) {
      stream.on(ev, self.emit.bind(self, ev));
    });

    // when we try to consume some more bytes, simply unpause the
    // underlying stream.
    self._read = function (n) {
      debug('wrapped _read', n);
      if (paused) {
        paused = false;
        stream.resume();
      }
    };

    return self;
  };

  // exposed for testing purposes only.
  Readable._fromList = fromList;

  // Pluck off n bytes from an array of buffers.
  // Length is the combined lengths of all the buffers in the list.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function fromList(n, state) {
    // nothing buffered
    if (state.length === 0) return null;

    var ret;
    if (state.objectMode) ret = state.buffer.shift();else if (!n || n >= state.length) {
      // read it all, truncate the list
      if (state.decoder) ret = state.buffer.join('');else if (state.buffer.length === 1) ret = state.buffer.head.data;else ret = state.buffer.concat(state.length);
      state.buffer.clear();
    } else {
      // read part of list
      ret = fromListPartial(n, state.buffer, state.decoder);
    }

    return ret;
  }

  // Extracts only enough buffered data to satisfy the amount requested.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function fromListPartial(n, list, hasStrings) {
    var ret;
    if (n < list.head.data.length) {
      // slice is the same for buffers and strings
      ret = list.head.data.slice(0, n);
      list.head.data = list.head.data.slice(n);
    } else if (n === list.head.data.length) {
      // first chunk is a perfect match
      ret = list.shift();
    } else {
      // result spans more than one buffer
      ret = hasStrings ? copyFromBufferString(n, list) : copyFromBuffer(n, list);
    }
    return ret;
  }

  // Copies a specified amount of characters from the list of buffered data
  // chunks.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function copyFromBufferString(n, list) {
    var p = list.head;
    var c = 1;
    var ret = p.data;
    n -= ret.length;
    while (p = p.next) {
      var str = p.data;
      var nb = n > str.length ? str.length : n;
      if (nb === str.length) ret += str;else ret += str.slice(0, n);
      n -= nb;
      if (n === 0) {
        if (nb === str.length) {
          ++c;
          if (p.next) list.head = p.next;else list.head = list.tail = null;
        } else {
          list.head = p;
          p.data = str.slice(nb);
        }
        break;
      }
      ++c;
    }
    list.length -= c;
    return ret;
  }

  // Copies a specified amount of bytes from the list of buffered data chunks.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function copyFromBuffer(n, list) {
    var ret = Buffer.allocUnsafe(n);
    var p = list.head;
    var c = 1;
    p.data.copy(ret);
    n -= p.data.length;
    while (p = p.next) {
      var buf = p.data;
      var nb = n > buf.length ? buf.length : n;
      buf.copy(ret, ret.length - n, 0, nb);
      n -= nb;
      if (n === 0) {
        if (nb === buf.length) {
          ++c;
          if (p.next) list.head = p.next;else list.head = list.tail = null;
        } else {
          list.head = p;
          p.data = buf.slice(nb);
        }
        break;
      }
      ++c;
    }
    list.length -= c;
    return ret;
  }

  function endReadable(stream) {
    var state = stream._readableState;

    // If we get here before consuming all the bytes, then that is a
    // bug in node.  Should never happen.
    if (state.length > 0) throw new Error('"endReadable()" called on non-empty stream');

    if (!state.endEmitted) {
      state.ended = true;
      nextTick(endReadableNT, state, stream);
    }
  }

  function endReadableNT(state, stream) {
    // Check that we didn't get one last unshift.
    if (!state.endEmitted && state.length === 0) {
      state.endEmitted = true;
      stream.readable = false;
      stream.emit('end');
    }
  }

  function forEach(xs, f) {
    for (var i = 0, l = xs.length; i < l; i++) {
      f(xs[i], i);
    }
  }

  function indexOf(xs, x) {
    for (var i = 0, l = xs.length; i < l; i++) {
      if (xs[i] === x) return i;
    }
    return -1;
  }

  // A bit simpler than readable streams.
  Writable.WritableState = WritableState;
  inherits$1(Writable, EventEmitter);

  function nop() {}

  function WriteReq(chunk, encoding, cb) {
    this.chunk = chunk;
    this.encoding = encoding;
    this.callback = cb;
    this.next = null;
  }

  function WritableState(options, stream) {
    Object.defineProperty(this, 'buffer', {
      get: deprecate(function () {
        return this.getBuffer();
      }, '_writableState.buffer is deprecated. Use _writableState.getBuffer ' + 'instead.')
    });
    options = options || {};

    // object stream flag to indicate whether or not this stream
    // contains buffers or objects.
    this.objectMode = !!options.objectMode;

    if (stream instanceof Duplex) this.objectMode = this.objectMode || !!options.writableObjectMode;

    // the point at which write() starts returning false
    // Note: 0 is a valid value, means that we always return false if
    // the entire buffer is not flushed immediately on write()
    var hwm = options.highWaterMark;
    var defaultHwm = this.objectMode ? 16 : 16 * 1024;
    this.highWaterMark = hwm || hwm === 0 ? hwm : defaultHwm;

    // cast to ints.
    this.highWaterMark = ~ ~this.highWaterMark;

    this.needDrain = false;
    // at the start of calling end()
    this.ending = false;
    // when end() has been called, and returned
    this.ended = false;
    // when 'finish' is emitted
    this.finished = false;

    // should we decode strings into buffers before passing to _write?
    // this is here so that some node-core streams can optimize string
    // handling at a lower level.
    var noDecode = options.decodeStrings === false;
    this.decodeStrings = !noDecode;

    // Crypto is kind of old and crusty.  Historically, its default string
    // encoding is 'binary' so we have to make this configurable.
    // Everything else in the universe uses 'utf8', though.
    this.defaultEncoding = options.defaultEncoding || 'utf8';

    // not an actual buffer we keep track of, but a measurement
    // of how much we're waiting to get pushed to some underlying
    // socket or file.
    this.length = 0;

    // a flag to see when we're in the middle of a write.
    this.writing = false;

    // when true all writes will be buffered until .uncork() call
    this.corked = 0;

    // a flag to be able to tell if the onwrite cb is called immediately,
    // or on a later tick.  We set this to true at first, because any
    // actions that shouldn't happen until "later" should generally also
    // not happen before the first write call.
    this.sync = true;

    // a flag to know if we're processing previously buffered items, which
    // may call the _write() callback in the same tick, so that we don't
    // end up in an overlapped onwrite situation.
    this.bufferProcessing = false;

    // the callback that's passed to _write(chunk,cb)
    this.onwrite = function (er) {
      onwrite(stream, er);
    };

    // the callback that the user supplies to write(chunk,encoding,cb)
    this.writecb = null;

    // the amount that is being written when _write is called.
    this.writelen = 0;

    this.bufferedRequest = null;
    this.lastBufferedRequest = null;

    // number of pending user-supplied write callbacks
    // this must be 0 before 'finish' can be emitted
    this.pendingcb = 0;

    // emit prefinish if the only thing we're waiting for is _write cbs
    // This is relevant for synchronous Transform streams
    this.prefinished = false;

    // True if the error was already emitted and should not be thrown again
    this.errorEmitted = false;

    // count buffered requests
    this.bufferedRequestCount = 0;

    // allocate the first CorkedRequest, there is always
    // one allocated and free to use, and we maintain at most two
    this.corkedRequestsFree = new CorkedRequest(this);
  }

  WritableState.prototype.getBuffer = function writableStateGetBuffer() {
    var current = this.bufferedRequest;
    var out = [];
    while (current) {
      out.push(current);
      current = current.next;
    }
    return out;
  };
  function Writable(options) {

    // Writable ctor is applied to Duplexes, though they're not
    // instanceof Writable, they're instanceof Readable.
    if (!(this instanceof Writable) && !(this instanceof Duplex)) return new Writable(options);

    this._writableState = new WritableState(options, this);

    // legacy.
    this.writable = true;

    if (options) {
      if (typeof options.write === 'function') this._write = options.write;

      if (typeof options.writev === 'function') this._writev = options.writev;
    }

    EventEmitter.call(this);
  }

  // Otherwise people can pipe Writable streams, which is just wrong.
  Writable.prototype.pipe = function () {
    this.emit('error', new Error('Cannot pipe, not readable'));
  };

  function writeAfterEnd(stream, cb) {
    var er = new Error('write after end');
    // TODO: defer error events consistently everywhere, not just the cb
    stream.emit('error', er);
    nextTick(cb, er);
  }

  // If we get something that is not a buffer, string, null, or undefined,
  // and we're not in objectMode, then that's an error.
  // Otherwise stream chunks are all considered to be of length=1, and the
  // watermarks determine how many objects to keep in the buffer, rather than
  // how many bytes or characters.
  function validChunk(stream, state, chunk, cb) {
    var valid = true;
    var er = false;
    // Always throw error if a null is written
    // if we are not in object mode then throw
    // if it is not a buffer, string, or undefined.
    if (chunk === null) {
      er = new TypeError('May not write null values to stream');
    } else if (!Buffer.isBuffer(chunk) && typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
      er = new TypeError('Invalid non-string/buffer chunk');
    }
    if (er) {
      stream.emit('error', er);
      nextTick(cb, er);
      valid = false;
    }
    return valid;
  }

  Writable.prototype.write = function (chunk, encoding, cb) {
    var state = this._writableState;
    var ret = false;

    if (typeof encoding === 'function') {
      cb = encoding;
      encoding = null;
    }

    if (Buffer.isBuffer(chunk)) encoding = 'buffer';else if (!encoding) encoding = state.defaultEncoding;

    if (typeof cb !== 'function') cb = nop;

    if (state.ended) writeAfterEnd(this, cb);else if (validChunk(this, state, chunk, cb)) {
      state.pendingcb++;
      ret = writeOrBuffer(this, state, chunk, encoding, cb);
    }

    return ret;
  };

  Writable.prototype.cork = function () {
    var state = this._writableState;

    state.corked++;
  };

  Writable.prototype.uncork = function () {
    var state = this._writableState;

    if (state.corked) {
      state.corked--;

      if (!state.writing && !state.corked && !state.finished && !state.bufferProcessing && state.bufferedRequest) clearBuffer(this, state);
    }
  };

  Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) {
    // node::ParseEncoding() requires lower case.
    if (typeof encoding === 'string') encoding = encoding.toLowerCase();
    if (!(['hex', 'utf8', 'utf-8', 'ascii', 'binary', 'base64', 'ucs2', 'ucs-2', 'utf16le', 'utf-16le', 'raw'].indexOf((encoding + '').toLowerCase()) > -1)) throw new TypeError('Unknown encoding: ' + encoding);
    this._writableState.defaultEncoding = encoding;
    return this;
  };

  function decodeChunk(state, chunk, encoding) {
    if (!state.objectMode && state.decodeStrings !== false && typeof chunk === 'string') {
      chunk = Buffer.from(chunk, encoding);
    }
    return chunk;
  }

  // if we're already writing something, then just put this
  // in the queue, and wait our turn.  Otherwise, call _write
  // If we return false, then we need a drain event, so set that flag.
  function writeOrBuffer(stream, state, chunk, encoding, cb) {
    chunk = decodeChunk(state, chunk, encoding);

    if (Buffer.isBuffer(chunk)) encoding = 'buffer';
    var len = state.objectMode ? 1 : chunk.length;

    state.length += len;

    var ret = state.length < state.highWaterMark;
    // we must ensure that previous needDrain will not be reset to false.
    if (!ret) state.needDrain = true;

    if (state.writing || state.corked) {
      var last = state.lastBufferedRequest;
      state.lastBufferedRequest = new WriteReq(chunk, encoding, cb);
      if (last) {
        last.next = state.lastBufferedRequest;
      } else {
        state.bufferedRequest = state.lastBufferedRequest;
      }
      state.bufferedRequestCount += 1;
    } else {
      doWrite(stream, state, false, len, chunk, encoding, cb);
    }

    return ret;
  }

  function doWrite(stream, state, writev, len, chunk, encoding, cb) {
    state.writelen = len;
    state.writecb = cb;
    state.writing = true;
    state.sync = true;
    if (writev) stream._writev(chunk, state.onwrite);else stream._write(chunk, encoding, state.onwrite);
    state.sync = false;
  }

  function onwriteError(stream, state, sync, er, cb) {
    --state.pendingcb;
    if (sync) nextTick(cb, er);else cb(er);

    stream._writableState.errorEmitted = true;
    stream.emit('error', er);
  }

  function onwriteStateUpdate(state) {
    state.writing = false;
    state.writecb = null;
    state.length -= state.writelen;
    state.writelen = 0;
  }

  function onwrite(stream, er) {
    var state = stream._writableState;
    var sync = state.sync;
    var cb = state.writecb;

    onwriteStateUpdate(state);

    if (er) onwriteError(stream, state, sync, er, cb);else {
      // Check if we're actually ready to finish, but don't emit yet
      var finished = needFinish(state);

      if (!finished && !state.corked && !state.bufferProcessing && state.bufferedRequest) {
        clearBuffer(stream, state);
      }

      if (sync) {
        /*<replacement>*/
          nextTick(afterWrite, stream, state, finished, cb);
        /*</replacement>*/
      } else {
          afterWrite(stream, state, finished, cb);
        }
    }
  }

  function afterWrite(stream, state, finished, cb) {
    if (!finished) onwriteDrain(stream, state);
    state.pendingcb--;
    cb();
    finishMaybe(stream, state);
  }

  // Must force callback to be called on nextTick, so that we don't
  // emit 'drain' before the write() consumer gets the 'false' return
  // value, and has a chance to attach a 'drain' listener.
  function onwriteDrain(stream, state) {
    if (state.length === 0 && state.needDrain) {
      state.needDrain = false;
      stream.emit('drain');
    }
  }

  // if there's something in the buffer waiting, then process it
  function clearBuffer(stream, state) {
    state.bufferProcessing = true;
    var entry = state.bufferedRequest;

    if (stream._writev && entry && entry.next) {
      // Fast case, write everything using _writev()
      var l = state.bufferedRequestCount;
      var buffer = new Array(l);
      var holder = state.corkedRequestsFree;
      holder.entry = entry;

      var count = 0;
      while (entry) {
        buffer[count] = entry;
        entry = entry.next;
        count += 1;
      }

      doWrite(stream, state, true, state.length, buffer, '', holder.finish);

      // doWrite is almost always async, defer these to save a bit of time
      // as the hot path ends with doWrite
      state.pendingcb++;
      state.lastBufferedRequest = null;
      if (holder.next) {
        state.corkedRequestsFree = holder.next;
        holder.next = null;
      } else {
        state.corkedRequestsFree = new CorkedRequest(state);
      }
    } else {
      // Slow case, write chunks one-by-one
      while (entry) {
        var chunk = entry.chunk;
        var encoding = entry.encoding;
        var cb = entry.callback;
        var len = state.objectMode ? 1 : chunk.length;

        doWrite(stream, state, false, len, chunk, encoding, cb);
        entry = entry.next;
        // if we didn't call the onwrite immediately, then
        // it means that we need to wait until it does.
        // also, that means that the chunk and cb are currently
        // being processed, so move the buffer counter past them.
        if (state.writing) {
          break;
        }
      }

      if (entry === null) state.lastBufferedRequest = null;
    }

    state.bufferedRequestCount = 0;
    state.bufferedRequest = entry;
    state.bufferProcessing = false;
  }

  Writable.prototype._write = function (chunk, encoding, cb) {
    cb(new Error('not implemented'));
  };

  Writable.prototype._writev = null;

  Writable.prototype.end = function (chunk, encoding, cb) {
    var state = this._writableState;

    if (typeof chunk === 'function') {
      cb = chunk;
      chunk = null;
      encoding = null;
    } else if (typeof encoding === 'function') {
      cb = encoding;
      encoding = null;
    }

    if (chunk !== null && chunk !== undefined) this.write(chunk, encoding);

    // .end() fully uncorks
    if (state.corked) {
      state.corked = 1;
      this.uncork();
    }

    // ignore unnecessary end() calls.
    if (!state.ending && !state.finished) endWritable(this, state, cb);
  };

  function needFinish(state) {
    return state.ending && state.length === 0 && state.bufferedRequest === null && !state.finished && !state.writing;
  }

  function prefinish(stream, state) {
    if (!state.prefinished) {
      state.prefinished = true;
      stream.emit('prefinish');
    }
  }

  function finishMaybe(stream, state) {
    var need = needFinish(state);
    if (need) {
      if (state.pendingcb === 0) {
        prefinish(stream, state);
        state.finished = true;
        stream.emit('finish');
      } else {
        prefinish(stream, state);
      }
    }
    return need;
  }

  function endWritable(stream, state, cb) {
    state.ending = true;
    finishMaybe(stream, state);
    if (cb) {
      if (state.finished) nextTick(cb);else stream.once('finish', cb);
    }
    state.ended = true;
    stream.writable = false;
  }

  // It seems a linked list but it is not
  // there will be only 2 of these for each stream
  function CorkedRequest(state) {
    var _this = this;

    this.next = null;
    this.entry = null;

    this.finish = function (err) {
      var entry = _this.entry;
      _this.entry = null;
      while (entry) {
        var cb = entry.callback;
        state.pendingcb--;
        cb(err);
        entry = entry.next;
      }
      if (state.corkedRequestsFree) {
        state.corkedRequestsFree.next = _this;
      } else {
        state.corkedRequestsFree = _this;
      }
    };
  }

  inherits$1(Duplex, Readable);

  var keys = Object.keys(Writable.prototype);
  for (var v = 0; v < keys.length; v++) {
    var method = keys[v];
    if (!Duplex.prototype[method]) Duplex.prototype[method] = Writable.prototype[method];
  }
  function Duplex(options) {
    if (!(this instanceof Duplex)) return new Duplex(options);

    Readable.call(this, options);
    Writable.call(this, options);

    if (options && options.readable === false) this.readable = false;

    if (options && options.writable === false) this.writable = false;

    this.allowHalfOpen = true;
    if (options && options.allowHalfOpen === false) this.allowHalfOpen = false;

    this.once('end', onend);
  }

  // the no-half-open enforcer
  function onend() {
    // if we allow half-open state, or if the writable side ended,
    // then we're ok.
    if (this.allowHalfOpen || this._writableState.ended) return;

    // no more data can be written.
    // But allow more writes to happen in this tick.
    nextTick(onEndNT, this);
  }

  function onEndNT(self) {
    self.end();
  }

  // a transform stream is a readable/writable stream where you do
  inherits$1(Transform, Duplex);

  function TransformState(stream) {
    this.afterTransform = function (er, data) {
      return afterTransform(stream, er, data);
    };

    this.needTransform = false;
    this.transforming = false;
    this.writecb = null;
    this.writechunk = null;
    this.writeencoding = null;
  }

  function afterTransform(stream, er, data) {
    var ts = stream._transformState;
    ts.transforming = false;

    var cb = ts.writecb;

    if (!cb) return stream.emit('error', new Error('no writecb in Transform class'));

    ts.writechunk = null;
    ts.writecb = null;

    if (data !== null && data !== undefined) stream.push(data);

    cb(er);

    var rs = stream._readableState;
    rs.reading = false;
    if (rs.needReadable || rs.length < rs.highWaterMark) {
      stream._read(rs.highWaterMark);
    }
  }
  function Transform(options) {
    if (!(this instanceof Transform)) return new Transform(options);

    Duplex.call(this, options);

    this._transformState = new TransformState(this);

    // when the writable side finishes, then flush out anything remaining.
    var stream = this;

    // start out asking for a readable event once data is transformed.
    this._readableState.needReadable = true;

    // we have implemented the _read method, and done the other things
    // that Readable wants before the first _read call, so unset the
    // sync guard flag.
    this._readableState.sync = false;

    if (options) {
      if (typeof options.transform === 'function') this._transform = options.transform;

      if (typeof options.flush === 'function') this._flush = options.flush;
    }

    this.once('prefinish', function () {
      if (typeof this._flush === 'function') this._flush(function (er) {
        done(stream, er);
      });else done(stream);
    });
  }

  Transform.prototype.push = function (chunk, encoding) {
    this._transformState.needTransform = false;
    return Duplex.prototype.push.call(this, chunk, encoding);
  };

  // This is the part where you do stuff!
  // override this function in implementation classes.
  // 'chunk' is an input chunk.
  //
  // Call `push(newChunk)` to pass along transformed output
  // to the readable side.  You may call 'push' zero or more times.
  //
  // Call `cb(err)` when you are done with this chunk.  If you pass
  // an error, then that'll put the hurt on the whole operation.  If you
  // never call cb(), then you'll never get another chunk.
  Transform.prototype._transform = function (chunk, encoding, cb) {
    throw new Error('Not implemented');
  };

  Transform.prototype._write = function (chunk, encoding, cb) {
    var ts = this._transformState;
    ts.writecb = cb;
    ts.writechunk = chunk;
    ts.writeencoding = encoding;
    if (!ts.transforming) {
      var rs = this._readableState;
      if (ts.needTransform || rs.needReadable || rs.length < rs.highWaterMark) this._read(rs.highWaterMark);
    }
  };

  // Doesn't matter what the args are here.
  // _transform does all the work.
  // That we got here means that the readable side wants more data.
  Transform.prototype._read = function (n) {
    var ts = this._transformState;

    if (ts.writechunk !== null && ts.writecb && !ts.transforming) {
      ts.transforming = true;
      this._transform(ts.writechunk, ts.writeencoding, ts.afterTransform);
    } else {
      // mark that we need a transform, so that any data that comes in
      // will get processed, now that we've asked for it.
      ts.needTransform = true;
    }
  };

  function done(stream, er) {
    if (er) return stream.emit('error', er);

    // if there's nothing in the write buffer, then that means
    // that nothing more will ever be provided
    var ws = stream._writableState;
    var ts = stream._transformState;

    if (ws.length) throw new Error('Calling transform done when ws.length != 0');

    if (ts.transforming) throw new Error('Calling transform done when still transforming');

    return stream.push(null);
  }

  inherits$1(PassThrough, Transform);
  function PassThrough(options) {
    if (!(this instanceof PassThrough)) return new PassThrough(options);

    Transform.call(this, options);
  }

  PassThrough.prototype._transform = function (chunk, encoding, cb) {
    cb(null, chunk);
  };

  inherits$1(Stream, EventEmitter);
  Stream.Readable = Readable;
  Stream.Writable = Writable;
  Stream.Duplex = Duplex;
  Stream.Transform = Transform;
  Stream.PassThrough = PassThrough;

  // Backwards-compat with node 0.4.x
  Stream.Stream = Stream;

  // old-style streams.  Note that the pipe method (the only relevant
  // part of this class) is overridden in the Readable class.

  function Stream() {
    EventEmitter.call(this);
  }

  Stream.prototype.pipe = function(dest, options) {
    var source = this;

    function ondata(chunk) {
      if (dest.writable) {
        if (false === dest.write(chunk) && source.pause) {
          source.pause();
        }
      }
    }

    source.on('data', ondata);

    function ondrain() {
      if (source.readable && source.resume) {
        source.resume();
      }
    }

    dest.on('drain', ondrain);

    // If the 'end' option is not supplied, dest.end() will be called when
    // source gets the 'end' or 'close' events.  Only dest.end() once.
    if (!dest._isStdio && (!options || options.end !== false)) {
      source.on('end', onend);
      source.on('close', onclose);
    }

    var didOnEnd = false;
    function onend() {
      if (didOnEnd) return;
      didOnEnd = true;

      dest.end();
    }


    function onclose() {
      if (didOnEnd) return;
      didOnEnd = true;

      if (typeof dest.destroy === 'function') dest.destroy();
    }

    // don't leave dangling pipes when there are errors.
    function onerror(er) {
      cleanup();
      if (EventEmitter.listenerCount(this, 'error') === 0) {
        throw er; // Unhandled stream error in pipe.
      }
    }

    source.on('error', onerror);
    dest.on('error', onerror);

    // remove all the event listeners that were added.
    function cleanup() {
      source.removeListener('data', ondata);
      dest.removeListener('drain', ondrain);

      source.removeListener('end', onend);
      source.removeListener('close', onclose);

      source.removeListener('error', onerror);
      dest.removeListener('error', onerror);

      source.removeListener('end', cleanup);
      source.removeListener('close', cleanup);

      dest.removeListener('close', cleanup);
    }

    source.on('end', cleanup);
    source.on('close', cleanup);

    dest.on('close', cleanup);

    dest.emit('pipe', source);

    // Allow for unix-like usage: A.pipe(B).pipe(C)
    return dest;
  };

  class CsvError extends Error {
    constructor(code, message, ...contexts) {
      if(Array.isArray(message)) message = message.join(' ');
      super(message);
      if(Error.captureStackTrace !== undefined){
        Error.captureStackTrace(this, CsvError);
      }
      this.code = code;
      for(const context of contexts){
        for(const key in context){
          const value = context[key];
          this[key] = isBuffer(value) ? value.toString() : value == null ? value : JSON.parse(JSON.stringify(value));
        }
      }
    }
  }

  const is_object = function(obj){
    return typeof obj === 'object' && obj !== null && ! Array.isArray(obj);
  };

  // Lodash implementation of `get`

  const charCodeOfDot = '.'.charCodeAt(0);
  const reEscapeChar = /\\(\\)?/g;
  const rePropName = RegExp(
    // Match anything that isn't a dot or bracket.
    '[^.[\\]]+' + '|' +
    // Or match property names within brackets.
    '\\[(?:' +
      // Match a non-string expression.
      '([^"\'][^[]*)' + '|' +
      // Or match strings (supports escaping characters).
      '(["\'])((?:(?!\\2)[^\\\\]|\\\\.)*?)\\2' +
    ')\\]'+ '|' +
    // Or match "" as the space between consecutive dots or empty brackets.
    '(?=(?:\\.|\\[\\])(?:\\.|\\[\\]|$))'
    , 'g');
  const reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\\]|\\.)*?\1)\]/;
  const reIsPlainProp = /^\w*$/;
  const getTag = function(value){
    return Object.prototype.toString.call(value);
  };
  const isSymbol = function(value){
    const type = typeof value;
    return type === 'symbol' || (type === 'object' && value && getTag(value) === '[object Symbol]');
  };
  const isKey = function(value, object){
    if(Array.isArray(value)){
      return false;
    }
    const type = typeof value;
    if(type === 'number' || type === 'symbol' || type === 'boolean' || !value || isSymbol(value)){
      return true;
    }
    return reIsPlainProp.test(value) || !reIsDeepProp.test(value) ||
      (object != null && value in Object(object));
  };
  const stringToPath = function(string){
    const result = [];
    if(string.charCodeAt(0) === charCodeOfDot){
      result.push('');
    }
    string.replace(rePropName, function(match, expression, quote, subString){
      let key = match;
      if(quote){
        key = subString.replace(reEscapeChar, '$1');
      }else if(expression){
        key = expression.trim();
      }
      result.push(key);
    });
    return result;
  };
  const castPath = function(value, object){
    if(Array.isArray(value)){
      return value;
    } else {
      return isKey(value, object) ? [value] : stringToPath(value);
    }
  };
  const toKey = function(value){
    if(typeof value === 'string' || isSymbol(value))
      return value;
    const result = `${value}`;
    // eslint-disable-next-line
    return (result == '0' && (1 / value) == -INFINITY) ? '-0' : result;
  };
  const get = function(object, path){
    path = castPath(path, object);
    let index = 0;
    const length = path.length;
    while(object != null && index < length){
      object = object[toKey(path[index++])];
    }
    return (index && index === length) ? object : undefined;
  };

  const normalize_columns = function(columns){
    if(columns === undefined || columns === null){
      return [undefined, undefined];
    }
    if(typeof columns !== 'object'){
      return [Error('Invalid option "columns": expect an array or an object')];
    }
    if(!Array.isArray(columns)){
      const newcolumns = [];
      for(const k in columns){
        newcolumns.push({
          key: k,
          header: columns[k]
        });
      }
      columns = newcolumns;
    }else {
      const newcolumns = [];
      for(const column of columns){
        if(typeof column === 'string'){
          newcolumns.push({
            key: column,
            header: column
          });
        }else if(typeof column === 'object' && column !== null && !Array.isArray(column)){
          if(!column.key){
            return [Error('Invalid column definition: property "key" is required')];
          }
          if(column.header === undefined){
            column.header = column.key;
          }
          newcolumns.push(column);
        }else {
          return [Error('Invalid column definition: expect a string or an object')];
        }
      }
      columns = newcolumns;
    }
    return [undefined, columns];
  };

  const underscore = function(str){
    return str.replace(/([A-Z])/g, function(_, match){
      return '_' + match.toLowerCase();
    });
  };

  const normalize_options = function(opts) {
    const options = {};
    // Merge with user options
    for(const opt in opts){
      options[underscore(opt)] = opts[opt];
    }
    // Normalize option `bom`
    if(options.bom === undefined || options.bom === null || options.bom === false){
      options.bom = false;
    }else if(options.bom !== true){
      return [new CsvError('CSV_OPTION_BOOLEAN_INVALID_TYPE', [
        'option `bom` is optional and must be a boolean value,',
        `got ${JSON.stringify(options.bom)}`
      ])];
    }
    // Normalize option `delimiter`
    if(options.delimiter === undefined || options.delimiter === null){
      options.delimiter = ',';
    }else if(isBuffer(options.delimiter)){
      options.delimiter = options.delimiter.toString();
    }else if(typeof options.delimiter !== 'string'){
      return [new CsvError('CSV_OPTION_DELIMITER_INVALID_TYPE', [
        'option `delimiter` must be a buffer or a string,',
        `got ${JSON.stringify(options.delimiter)}`
      ])];
    }
    // Normalize option `quote`
    if(options.quote === undefined || options.quote === null){
      options.quote = '"';
    }else if(options.quote === true){
      options.quote = '"';
    }else if(options.quote === false){
      options.quote = '';
    }else if (isBuffer(options.quote)){
      options.quote = options.quote.toString();
    }else if(typeof options.quote !== 'string'){
      return [new CsvError('CSV_OPTION_QUOTE_INVALID_TYPE', [
        'option `quote` must be a boolean, a buffer or a string,',
        `got ${JSON.stringify(options.quote)}`
      ])];
    }
    // Normalize option `quoted`
    if(options.quoted === undefined || options.quoted === null){
      options.quoted = false;
    }
    // Normalize option `quoted_empty`
    if(options.quoted_empty === undefined || options.quoted_empty === null){
      options.quoted_empty = undefined;
    }
    // Normalize option `quoted_match`
    if(options.quoted_match === undefined || options.quoted_match === null || options.quoted_match === false){
      options.quoted_match = null;
    }else if(!Array.isArray(options.quoted_match)){
      options.quoted_match = [options.quoted_match];
    }
    if(options.quoted_match){
      for(const quoted_match of options.quoted_match){
        const isString = typeof quoted_match === 'string';
        const isRegExp = quoted_match instanceof RegExp;
        if(!isString && !isRegExp){
          return [Error(`Invalid Option: quoted_match must be a string or a regex, got ${JSON.stringify(quoted_match)}`)];
        }
      }
    }
    // Normalize option `quoted_string`
    if(options.quoted_string === undefined || options.quoted_string === null){
      options.quoted_string = false;
    }
    // Normalize option `eof`
    if(options.eof === undefined || options.eof === null){
      options.eof = true;
    }
    // Normalize option `escape`
    if(options.escape === undefined || options.escape === null){
      options.escape = '"';
    }else if(isBuffer(options.escape)){
      options.escape = options.escape.toString();
    }else if(typeof options.escape !== 'string'){
      return [Error(`Invalid Option: escape must be a buffer or a string, got ${JSON.stringify(options.escape)}`)];
    }
    if (options.escape.length > 1){
      return [Error(`Invalid Option: escape must be one character, got ${options.escape.length} characters`)];
    }
    // Normalize option `header`
    if(options.header === undefined || options.header === null){
      options.header = false;
    }
    // Normalize option `columns`
    const [errColumns, columns] = normalize_columns(options.columns);
    if(errColumns !== undefined) return [errColumns];
    options.columns = columns;
    // Normalize option `quoted`
    if(options.quoted === undefined || options.quoted === null){
      options.quoted = false;
    }
    // Normalize option `cast`
    if(options.cast === undefined || options.cast === null){
      options.cast = {};
    }
    // Normalize option cast.bigint
    if(options.cast.bigint === undefined || options.cast.bigint === null){
      // Cast boolean to string by default
      options.cast.bigint = value => '' + value;
    }
    // Normalize option cast.boolean
    if(options.cast.boolean === undefined || options.cast.boolean === null){
      // Cast boolean to string by default
      options.cast.boolean = value => value ? '1' : '';
    }
    // Normalize option cast.date
    if(options.cast.date === undefined || options.cast.date === null){
      // Cast date to timestamp string by default
      options.cast.date = value => '' + value.getTime();
    }
    // Normalize option cast.number
    if(options.cast.number === undefined || options.cast.number === null){
      // Cast number to string using native casting by default
      options.cast.number = value => '' + value;
    }
    // Normalize option cast.object
    if(options.cast.object === undefined || options.cast.object === null){
      // Stringify object as JSON by default
      options.cast.object = value => JSON.stringify(value);
    }
    // Normalize option cast.string
    if(options.cast.string === undefined || options.cast.string === null){
      // Leave string untouched
      options.cast.string = function(value){return value;};
    }
    // Normalize option `on_record`
    if(options.on_record !== undefined && typeof options.on_record !== 'function'){
      return [Error(`Invalid Option: "on_record" must be a function.`)];
    }
    // Normalize option `record_delimiter`
    if(options.record_delimiter === undefined || options.record_delimiter === null){
      options.record_delimiter = '\n';
    }else if(isBuffer(options.record_delimiter)){
      options.record_delimiter = options.record_delimiter.toString();
    }else if(typeof options.record_delimiter !== 'string'){
      return [Error(`Invalid Option: record_delimiter must be a buffer or a string, got ${JSON.stringify(options.record_delimiter)}`)];
    }
    switch(options.record_delimiter){
    case 'auto':
      options.record_delimiter = null;
      break;
    case 'unix':
      options.record_delimiter = "\n";
      break;
    case 'mac':
      options.record_delimiter = "\r";
      break;
    case 'windows':
      options.record_delimiter = "\r\n";
      break;
    case 'ascii':
      options.record_delimiter = "\u001e";
      break;
    case 'unicode':
      options.record_delimiter = "\u2028";
      break;
    }
    return [undefined, options];
  };

  const bom_utf8 = Buffer.from([239, 187, 191]);

  const stringifier = function(options, state, info){
    return {
      options: options,
      state: state,
      info: info,
      __transform: function(chunk, push){
        // Chunk validation
        if(!Array.isArray(chunk) && typeof chunk !== 'object'){
          return Error(`Invalid Record: expect an array or an object, got ${JSON.stringify(chunk)}`);
        }
        // Detect columns from the first record
        if(this.info.records === 0){
          if(Array.isArray(chunk)){
            if(this.options.header === true && this.options.columns === undefined){
              return Error('Undiscoverable Columns: header option requires column option or object records');
            }
          }else if(this.options.columns === undefined){
            const [err, columns] = normalize_columns(Object.keys(chunk));
            if(err) return;
            this.options.columns = columns;
          }
        }
        // Emit the header
        if(this.info.records === 0){
          this.bom(push);
          const err = this.headers(push);
          if(err) return err;
        }
        // Emit and stringify the record if an object or an array
        try{
          // this.emit('record', chunk, this.info.records);
          if(this.options.on_record){
            this.options.on_record(chunk, this.info.records);
          }
        }catch(err){
          return err;
        }
        // Convert the record into a string
        let err, chunk_string;
        if(this.options.eof){
          [err, chunk_string] = this.stringify(chunk);
          if(err) return err;
          if(chunk_string === undefined){
            return;
          }else {
            chunk_string = chunk_string + this.options.record_delimiter;
          }
        }else {
          [err, chunk_string] = this.stringify(chunk);
          if(err) return err;
          if(chunk_string === undefined){
            return;
          }else {
            if(this.options.header || this.info.records){
              chunk_string = this.options.record_delimiter + chunk_string;
            }
          }
        }
        // Emit the csv
        this.info.records++;
        push(chunk_string);
      },
      stringify: function(chunk, chunkIsHeader=false){
        if(typeof chunk !== 'object'){
          return [undefined, chunk];
        }
        const {columns} = this.options;
        const record = [];
        // Record is an array
        if(Array.isArray(chunk)){
          // We are getting an array but the user has specified output columns. In
          // this case, we respect the columns indexes
          if(columns){
            chunk.splice(columns.length);
          }
          // Cast record elements
          for(let i=0; i<chunk.length; i++){
            const field = chunk[i];
            const [err, value] = this.__cast(field, {
              index: i, column: i, records: this.info.records, header: chunkIsHeader
            });
            if(err) return [err];
            record[i] = [value, field];
          }
        // Record is a literal object
        // `columns` is always defined: it is either provided or discovered.
        }else {
          for(let i=0; i<columns.length; i++){
            const field = get(chunk, columns[i].key);
            const [err, value] = this.__cast(field, {
              index: i, column: columns[i].key, records: this.info.records, header: chunkIsHeader
            });
            if(err) return [err];
            record[i] = [value, field];
          }
        }
        let csvrecord = '';
        for(let i=0; i<record.length; i++){
          let options, err;
          // eslint-disable-next-line
          let [value, field] = record[i];
          if(typeof value === "string"){
            options = this.options;
          }else if(is_object(value)){
            options = value;
            value = options.value;
            delete options.value;
            if(typeof value !== "string" && value !== undefined && value !== null){
              if(err) return [Error(`Invalid Casting Value: returned value must return a string, null or undefined, got ${JSON.stringify(value)}`)];
            }
            options = {...this.options, ...options};
            [err, options] = normalize_options(options);
            if(err !== undefined){
              return [err];
            }
          }else if(value === undefined || value === null){
            options = this.options;
          }else {
            return [Error(`Invalid Casting Value: returned value must return a string, an object, null or undefined, got ${JSON.stringify(value)}`)];
          }
          const {delimiter, escape, quote, quoted, quoted_empty, quoted_string, quoted_match, record_delimiter} = options;
          if('' === value && '' === field){
            let quotedMatch = quoted_match && quoted_match.filter(quoted_match => {
              if(typeof quoted_match === 'string'){
                return value.indexOf(quoted_match) !== -1;
              }else {
                return quoted_match.test(value);
              }
            });
            quotedMatch = quotedMatch && quotedMatch.length > 0;
            const shouldQuote = quotedMatch || true === quoted_empty ||
              (true === quoted_string && false !== quoted_empty);
            if(shouldQuote === true){
              value = quote + value + quote;
            }
            csvrecord += value;
          }else if(value){
            if(typeof value !== 'string'){
              return [Error(`Formatter must return a string, null or undefined, got ${JSON.stringify(value)}`)];
            }
            const containsdelimiter = delimiter.length && value.indexOf(delimiter) >= 0;
            const containsQuote = (quote !== '') && value.indexOf(quote) >= 0;
            const containsEscape = value.indexOf(escape) >= 0 && (escape !== quote);
            const containsRecordDelimiter = value.indexOf(record_delimiter) >= 0;
            const quotedString = quoted_string && typeof field === 'string';
            let quotedMatch = quoted_match && quoted_match.filter(quoted_match => {
              if(typeof quoted_match === 'string'){
                return value.indexOf(quoted_match) !== -1;
              }else {
                return quoted_match.test(value);
              }
            });
            quotedMatch = quotedMatch && quotedMatch.length > 0;
            const shouldQuote = containsQuote === true || containsdelimiter || containsRecordDelimiter || quoted || quotedString || quotedMatch;
            if(shouldQuote === true && containsEscape === true){
              const regexp = escape === '\\'
                ? new RegExp(escape + escape, 'g')
                : new RegExp(escape, 'g');
              value = value.replace(regexp, escape + escape);
            }
            if(containsQuote === true){
              const regexp = new RegExp(quote,'g');
              value = value.replace(regexp, escape + quote);
            }
            if(shouldQuote === true){
              value = quote + value + quote;
            }
            csvrecord += value;
          }else if(quoted_empty === true || (field === '' && quoted_string === true && quoted_empty !== false)){
            csvrecord += quote + quote;
          }
          if(i !== record.length - 1){
            csvrecord += delimiter;
          }
        }
        return [undefined, csvrecord];
      },
      bom: function(push){
        if(this.options.bom !== true){
          return;
        }
        push(bom_utf8);
      },
      headers: function(push){
        if(this.options.header === false){
          return;
        }
        if(this.options.columns === undefined){
          return;
        }
        let err;
        let headers = this.options.columns.map(column => column.header);
        if(this.options.eof){
          [err, headers] = this.stringify(headers, true);
          headers += this.options.record_delimiter;
        }else {
          [err, headers] = this.stringify(headers);
        }
        if(err) return err;
        push(headers);
      },
      __cast: function(value, context){
        const type = typeof value;
        try{
          if(type === 'string'){ // Fine for 99% of the cases
            return [undefined, this.options.cast.string(value, context)];
          }else if(type === 'bigint'){
            return [undefined, this.options.cast.bigint(value, context)];
          }else if(type === 'number'){
            return [undefined, this.options.cast.number(value, context)];
          }else if(type === 'boolean'){
            return [undefined, this.options.cast.boolean(value, context)];
          }else if(value instanceof Date){
            return [undefined, this.options.cast.date(value, context)];
          }else if(type === 'object' && value !== null){
            return [undefined, this.options.cast.object(value, context)];
          }else {
            return [undefined, value, value];
          }
        }catch(err){
          return [err];
        }
      }
    };
  };

  class Stringifier extends Transform {
    constructor(opts = {}){
      super({...{writableObjectMode: true}, ...opts});
      const [err, options] = normalize_options(opts);
      if(err !== undefined) throw err;
      // Expose options
      this.options = options;
      // Internal state
      this.state = {
        stop: false
      };
      // Information
      this.info = {
        records: 0
      };
      this.api = stringifier(this.options, this.state, this.info);
      this.api.options.on_record = (...args) => {
        this.emit('record', ...args);
      };
    }
    _transform(chunk, encoding, callback){
      if(this.state.stop === true){
        return;
      }
      const err = this.api.__transform(chunk, this.push.bind(this));
      if(err !== undefined){
        this.state.stop = true;
      }
      callback(err);
    }
    _flush(callback){
      if(this.state.stop === true){
        // Note, Node.js 12 call flush even after an error, we must prevent
        // `callback` from being called in flush without any error.
        return;
      }
      if(this.info.records === 0){
        this.api.bom(this.push.bind(this));
        const err = this.api.headers(this.push.bind(this));
        if(err) callback(err);
      }
      callback();
    }
  }

  const stringify = function(){
    let data, options, callback;
    for(const i in arguments){
      const argument = arguments[i];
      const type = typeof argument;
      if(data === undefined && (Array.isArray(argument))){
        data = argument;
      }else if(options === undefined && is_object(argument)){
        options = argument;
      }else if(callback === undefined && type === 'function'){
        callback = argument;
      }else {
        throw new CsvError('CSV_INVALID_ARGUMENT', [
          'Invalid argument:',
          `got ${JSON.stringify(argument)} at index ${i}`
        ]);
      }
    }
    const stringifier = new Stringifier(options);
    if(callback){
      const chunks = [];
      stringifier.on('readable', function(){
        let chunk;
        while((chunk = this.read()) !== null){
          chunks.push(chunk);
        }
      });
      stringifier.on('error', function(err){
        callback(err);
      });
      stringifier.on('end', function(){
        callback(undefined, chunks.join(''));
      });
    }
    if(data !== undefined){
      const writer = function(){
        for(const record of data){
          stringifier.write(record);
        }
        stringifier.end();
      };
      // Support Deno, Rollup doesnt provide a shim for setImmediate
      if(typeof setImmediate === 'function'){
        setImmediate(writer);
      }else {
        setTimeout(writer, 0);
      }
    }
    return stringifier;
  };

  exports.CsvError = CsvError;
  exports.Stringifier = Stringifier;
  exports.stringify = stringify;

  Object.defineProperty(exports, '__esModule', { value: true });

}));