docs: def _init_topics(self):
          """Set up initial subscription of mysensors topics."""
          _LOGGER.info('Setting up initial MQTT topic subscription')
          init_topics = [
              '{}/+/+/0/+/+'.format(self._in_prefix),
              '{}/+/+/3/+/+'.format(self._in_prefix),
          ]
          self._handle_subscription(init_topics)
          if not self.persistence:
              return
          topics = [
              '{}/{}/{}/{}/+/+'.format(
                  self._in_prefix, str(sensor.sensor_id), str(child.id),
                  msg_type) for sensor in self.sensors.values()
              for child in sensor.children.values()
              for msg_type in (int(self.const.MessageType.set),
                               int(self.const.MessageType.req))
          ]
          topics.extend([
              '{}/{}/+/{}/+/+'.format(
                  self._in_prefix, str(sensor.sensor_id),
                  int(self.const.MessageType.stream))
              for sensor in self.sensors.values()])
          self._handle_subscription(topics)