Add type hints to some handlers (#8505)

synapse/handlers/read_marker.py

@@ -14,23 +14,29 @@
 # limitations under the License.
 
 import logging
+from typing import TYPE_CHECKING
 
 from synapse.util.async_helpers import Linearizer
 
 from ._base import BaseHandler
 
+if TYPE_CHECKING:
+    from synapse.app.homeserver import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
 class ReadMarkerHandler(BaseHandler):
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
         self.server_name = hs.config.server_name
         self.store = hs.get_datastore()
         self.read_marker_linearizer = Linearizer(name="read_marker")
         self.notifier = hs.get_notifier()
 
-    async def received_client_read_marker(self, room_id, user_id, event_id):
+    async def received_client_read_marker(
+        self, room_id: str, user_id: str, event_id: str
+    ) -> None:
         """Updates the read marker for a given user in a given room if the event ID given
         is ahead in the stream relative to the current read marker.