def connect_and_subscribe():
client_id = ubinascii.hexlify(machine.unique_id())
mqtt_server = credentials.mqtt_server
topic_sub = credentials.topic
client = MQTTClient(client_id, mqtt_server)
client.user = credentials.user
client.pswd = credentials.pswd
client.set_callback(sub_cb)
client.connect()
client.subscribe(topic_sub)
print('Connected to %s MQTT broker, subscribed to %s topic' %
(mqtt_server, topic_sub))
return client
