Now, we will use the previously coded functions to write a __main__ method that publishes many commands included in MQTT messages that the code controlling the drone will process. The following lines show the code for the __main__ method, that is, the main block of code. The code file for the sample is included in the mqtt_essentials_gaston_hillar_03 folder, in the mqtt_essentials_example03_03.py file:
if __name__ == "__main__":
client = mqtt.Client(protocol=mqtt.MQTTv311)
client.on_connect = on_connect
client.on_subscribe = on_subscribe
client.on_message = on_message
client.tls_set(ca_certs = ca_certificate,
certfile=client_certificate,
keyfile=client_key)
client.connect(host=mqtt_server_host,
port=mqtt_server_port,
keepalive=mqtt_keepalive)
publish_command(client, CMD_TAKE_OFF)
publish_command(client, CMD_MOVE_UP)
publish_command(client, CMD_ROTATE_LEFT, KEY_DEGREES, 90)
publish_command...