def METHOD_NAME(client, userdata, msg):  # type: (mqtt.Client, tuple, mqtt.client.MQTTMessage) -> None
    _ = userdata
    global message_log
    payload = msg.payload.decode()
    if not event_client_received_correct.is_set() and payload == 'data':
        client.publish('/topic/qos0', 'data_to_esp32')
        if msg.topic == '/topic/qos0' and payload == 'data':
            event_client_received_correct.set()
    message_log += 'Received data:' + msg.topic + ' ' + payload + '\n'