code: def enter_room(self, sid, room, namespace=None):
          
          namespace = namespace or '/'
          self.logger.info('%s is entering room %s [%s]', sid, room, namespace)
          self.manager.enter_room(sid, namespace, room)
docs: Enter a room.
  
          This function adds the client to a room. The :func:`emit` and
          :func:`send` functions can optionally broadcast events to all the
          clients in a room.
  
          :param sid: Session ID of the client.
          :param room: Room name. If the room does not exist it is created.
          :param namespace: The Socket.IO namespace for the event. If this
                            argument is omitted the default namespace is used.