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

def chat(room=None, stream=None, **kwargs):
    """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

    """
    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