code: def subscribe_topics(self):
          
          base = self.topic
          subscribe = self.mqtt.subscribe
  
          # device topics
          subscribe(b"/".join((base, b"$stats/interval/set")))
          subscribe(b"/".join((self.settings.MQTT_BASE_TOPIC, b"$broadcast/#")))
  
          # node topics
          nodes = self.nodes
          for node in nodes:
              for topic in node.subscribe:
                  topic = b"/".join((base, topic))
                  # print('MQTT SUBSCRIBE: {}'.format(topic))
                  subscribe(topic)
                  self.topic_callbacks[topic] = node.callback
docs: subscribe to all registered device and node topics