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.

def enter_room(self, sid, room, namespace=None):
        """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.
        """
        namespace = namespace or '/'
        self.logger.info('%s is entering room %s [%s]', sid, room, namespace)
        self.manager.enter_room(sid, namespace, room)