code: def unsubscribe(self, topic):
          
          try:
              tmp = self._mqttc
          except AttributeError:
              logger.info('No MQTT Client instance found so nothing to unsubscribe from.')
              return
  
          if self._background_mqttc:
              logger.info('Closing background loop')
              self._background_mqttc.loop_stop()
              self._background_mqttc = None
  
          if topic in self._messages:
              del self._messages[topic]
  
          logger.info('Unsubscribing from topic: %s' % topic)
          self._unsubscribed = False
          self._mqttc.on_unsubscribe = self._on_unsubscribe
          self._mqttc.unsubscribe(str(topic))
  
          timer_start = time.time()
          while (not self._unsubscribed and
                  time.time() < timer_start + self._loop_timeout):
              self._mqttc.loop()
  
          if not self._unsubscribed:
              logger.warn('Client didn\'t receive an unsubscribe callback')
docs: Unsubscribe the client from the specified topic.
  
          `topic` topic to unsubscribe from
  
          Example:
          | Unsubscribe | test/mqtt_test |