def close_stream(data_type, stream_id):
    """
    Construct a 'closeStream' message to close an open stream between the client and server, by the server.
    :param data_type: int the RTMP datatype.
    :param stream_id: int the stream which the message will be sent on.
    """
    msg = {'msg': data_type,
           'stream_id': stream_id,
           'command': [u'closeStream', 0, None]}
    return msg