Enable type hints for servlet file.

Author: clokep

mypy.ini

@@ -32,6 +32,7 @@ files =
   synapse/http/federation/matrix_federation_agent.py,
   synapse/http/federation/well_known_resolver.py,
   synapse/http/matrixfederationclient.py,
+  synapse/http/servlet.py,
   synapse/http/server.py,
   synapse/http/site.py,
   synapse/logging,

synapse/http/servlet.py

@@ -197,8 +197,9 @@ def parse_string(
             parameter is present, must be one of a list of allowed values and
             is not one of those allowed values.
     """
+    args = request.args  # type: Dict[bytes, List[bytes]]  # type: ignore
     return parse_string_from_args(
-        request.args, name, default, required, allowed_values, encoding
+        args, name, default, required, allowed_values, encoding
     )
 
 
@@ -422,9 +423,8 @@ class attribute containing a pre-compiled regular expression. The automatic
 
     def register(self, http_server):
         """ Register this servlet with the given HTTP server. """
-        if hasattr(self, "PATTERNS"):
-            patterns = self.PATTERNS
-
+        patterns = getattr(self, "PATTERNS", None)
+        if patterns:
             for method in ("GET", "PUT", "POST", "DELETE"):
                 if hasattr(self, "on_%s" % (method,)):
                     servlet_classname = self.__class__.__name__