Snippet from my "exit if disabled" micropython code

foo.py

def main():
    connect_and_subscribe()
    if check_disabled():
        log('Exiting because disabled.')
        return
    read_sensor()
    finish()

def connect_and_subscribe():
    """Connect to the MQTT server and subscribe to interesting topics."""
    global c
    c = umqtt.simple.MQTTClient('umqtt_client', MQTT_SERVER)
    log(f'Connected to {MQTT_SERVER}')
    c.set_callback(receive_message)
    c.connect()
    c.subscribe(topic(DISABLE_TOPIC))

def receive_message(top, msg):
    global disabled
    log('Received "%s" "%s"' % (top.decode('utf-8'), msg.decode('utf-8')))
    if top == topic(DISABLE_TOPIC) and msg != b'false':
        disabled = True

def check_disabled():
    """Checks, a couple times, if we are supposed to disable ourselves."""
    c.check_msg()
    if disabled:
        return disabled
    time.sleep(1)
    c.check_msg()
    return disabled