Merge pull request #3253 from aligoren/document-get-exc-class-and-code

Added :param to the _get_exc_class_and_code method docstring

flask/app.py

@@ -1270,7 +1270,13 @@ class Flask(_PackageBoundObject):
 
     @staticmethod
     def _get_exc_class_and_code(exc_class_or_code):
-        """Ensure that we register only exceptions as handler keys"""
+        """Get the exception class being handled. For HTTP status codes
+        or ``HTTPException`` subclasses, return both the exception and
+        status code.
+
+        :param exc_class_or_code: Any exception class, or an HTTP status
+            code as an integer.
+        """
         if isinstance(exc_class_or_code, integer_types):
             exc_class = default_exceptions[exc_class_or_code]
         else: