feat: add more type hints

falcon/app.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 
 """Falcon App class."""
-
 from functools import wraps
 from inspect import iscoroutinefunction
 import pathlib
@@ -42,7 +41,6 @@
 from falcon.util import misc
 from falcon.util.misc import code_to_http_status
 
-
 # PERF(vytas): On Python 3.5+ (including cythonized modules),
 # reference via module global is faster than going via self
 _BODILESS_STATUS_CODES = frozenset(
@@ -673,7 +671,7 @@ def add_static_route(
         self._static_routes.insert(0, (sr, sr, False))
         self._update_sink_and_static_routes()
 
-    def add_sink(self, sink: Callable, prefix: SinkPrefix = r'/'):
+    def add_sink(self, sink: Callable, prefix: SinkPrefix = r'/') -> None:
         """Register a sink method for the App.
 
         If no route matches a request, but the path in the requested URI

falcon/app_helpers.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 """Utilities for the App class."""
+from __future__ import annotations
 
 from inspect import iscoroutinefunction
 from typing import IO, Iterable, List, Tuple
@@ -201,7 +202,7 @@ def prepare_middleware_ws(middleware: Iterable) -> Tuple[list, list]:
     return request_mw, resource_mw
 
 
-def default_serialize_error(req: Request, resp: Response, exception: HTTPError):
+def default_serialize_error(req: Request, resp: Response, exception: HTTPError) -> None:
     """Serialize the given instance of HTTPError.
 
     This function determines which of the supported media types, if
@@ -280,22 +281,22 @@ class CloseableStreamIterator:
         block_size (int): Number of bytes to read per iteration.
     """
 
-    def __init__(self, stream: IO, block_size: int):
+    def __init__(self, stream: IO, block_size: int) -> None:
         self._stream = stream
         self._block_size = block_size
 
-    def __iter__(self):
+    def __iter__(self) -> CloseableStreamIterator:
         return self
 
-    def __next__(self):
+    def __next__(self) -> bytes:
         data = self._stream.read(self._block_size)
 
         if data == b'':
             raise StopIteration
         else:
             return data
 
-    def close(self):
+    def close(self) -> None:
         try:
             self._stream.close()
         except (AttributeError, TypeError):

falcon/asgi_spec.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 """Constants, etc. defined by the ASGI specification."""
+from __future__ import annotations
 
 
 class EventType: