code: def chat(room=None, stream=None, **kwargs):
      
      if room is None:
          room = _random_room()
          print("room =", room)
      if stream is None:
          stream = CameraStream()
      room = WebRTCRoomMqtt(stream=stream, room=room)
      box = widgets.HBox(children=[])
      widgets.jslink((room, 'streams'), (box, 'children'))
      display(box)
      return room
docs: Quick setup for a chatroom.
  
      :param str room: Roomname, if not given, a random sequence is generated and printed.
      :param MediaStream stream: The media stream to share, if not given a CameraStream will be created.
      :rtype: WebRTCRoom