1 files changed, 4 insertions, 0 deletions
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 1660921306..4d20ed8357 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -155,6 +155,10 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
         """
         raise NotImplementedError()
 
+    @abc.abstractmethod
+    async def forget(self, user: UserID, room_id: str) -> None:
+        raise NotImplementedError()
+
     def ratelimit_invite(self, room_id: Optional[str], invitee_user_id: str):
         """Ratelimit invites by room and by target user.