refactor: model: Loop over potential streams and user in peer events.

Author: neiljp

zulipterminal/model.py

@@ -783,11 +783,17 @@ def get_stream_by_id(streams: List[StreamData], stream_id: int
                     sort_streams(self.pinned_streams)
                     self.controller.view.left_panel.update_stream_view()
                     self.controller.update_screen()
-        elif (event['op'] in ('peer_add', 'peer_remove')
-              and self.is_user_subscribed_to_stream(event['stream_id'])):
+        elif event['op'] in ('peer_add', 'peer_remove'):
             action_map = dict(peer_add='append', peer_remove='remove')
-            peers = self.stream_dict[event['stream_id']]['subscribers']
-            getattr(peers, action_map[event['op']])(event['user_id'])
+            peers_action = action_map[event['op']]
+            stream_ids = [event['stream_id']]
+            user_ids = [event['user_id']]
+            for stream_id in stream_ids:
+                if self.is_user_subscribed_to_stream(stream_id):
+                    peers = self.stream_dict[stream_id]['subscribers']
+                    action = getattr(peers, peers_action)
+                    for user_id in user_ids:
+                        action(user_id)
 
     def _handle_typing_event(self, event: Event) -> None:
         """