docs: def _parse_mqtt_to_message(self, topic, payload, qos):
          """Parse a MQTT topic and payload.
  
          Return a mysensors command string.
          """
          topic_levels = topic.split('/')
          topic_levels = not_prefix = topic_levels[-5:]
          prefix_end_idx = topic.find('/'.join(not_prefix)) - 1
          prefix = topic[:prefix_end_idx]
          if prefix != self._in_prefix:
              return None
          if qos and qos > 0:
              ack = '1'
          else:
              ack = '0'
          topic_levels[3] = ack
          topic_levels.append(str(payload))
          return ';'.join(topic_levels)