@staticmethod
def on_publish_finished(client, request_id):
    """called when a message that was to be sent using the publish() call has completed transmission to the broker.
        For messages with QoS levels 1 and 2, this means that the appropriate handshakes have completed. For QoS 0,
        this simply means that the message has left the client.

        request_id -- the identifier of the publish request"""
    pass
