code: def leave_room(room, sid=None, namespace=None):
      
      socketio = flask.current_app.extensions['socketio']
      sid = sid or flask.request.sid
      namespace = namespace or flask.request.namespace
      socketio.server.leave_room(sid, room, namespace=namespace)
docs: Leave a room.
  
      This function removes the user from a room, under the current namespace.
      The user and the namespace are obtained from the event context. Example::
  
          @socketio.on('leave')
          def on_leave(data):
              username = session['username']
              room = data['room']
              leave_room(room)
              send(username + ' has left the room.', room=room)
  
      :param room: The name of the room to leave.
      :param sid: The session id of the client. If not provided, the client is
                  obtained from the request context.
      :param namespace: The namespace for the room. If not provided, the
                        namespace is obtained from the request context.