code: def backfill_previous_messages(self, reverse=False, limit=10):
          
          res = self.client.api.get_room_messages(self.room_id, self.prev_batch,
                                                  direction="b", limit=limit)
          events = res["chunk"]
          if not reverse:
              events = reversed(events)
          for event in events:
              self._put_event(event)
docs: Backfill handling of previous messages.
  
          Args:
              reverse (bool): When false messages will be backfilled in their original
                  order (old to new), otherwise the order will be reversed (new to old).
              limit (int): Number of messages to go back.