Add "wrap" to exports.

Fixes a bug introduced in #410.

exports.js

@@ -2,7 +2,7 @@ module.exports = function() {
   var result = {};
 
   for (var prop in this) {
-    if (!this.hasOwnProperty(prop) || prop.match(/^(?:include|contains|reverse|join|map)$/)) continue;
+    if (!this.hasOwnProperty(prop) || prop.match(/^(?:include|contains|reverse|join|map|wrap)$/)) continue;
     result[prop] = this[prop];
   }