code: def unsubscribe(self, topics):
          
          yield from self._handler.mqtt_unsubscribe(topics, self.session.next_packet_id)
docs: Unsubscribe from some topics.
  
              Send a MQTT `UNSUBSCRIBE <http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718072>`_ message and wait for broker `UNSUBACK <http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718077>`_ message.
  
              This method is a *coroutine*.
  
              :param topics: array of topics to unsubscribe from.
  
              Example of ``topics`` argument expected structure:
              ::
  
                  ['$SYS/broker/uptime', '$SYS/broker/load/#']