import time
from umqtt.simple import MQTTClient
def sub_cb(topic, msg):
print((topic, msg))
c = MQTTClient("uqmtt_client", "localhost")
c.connect()
c.subscribe(b"foo_topic")
c.publish(b"foo_topic", b"hello")
while 1:
c.wait_msg()
c.disconnect()