code: def get_value(self):
          
          yield self._manager.poll_sensor(self._name)
          # By now the sensor manager should have set the reading
          raise Return(self._reading.value)
docs: Get a fresh sensor value from the KATCP resource
  
          Returns
          -------
          reply : tornado Future resolving with  :class:`KATCPSensorReading` object
  
          Note
          ----
  
          As a side-effect this will update the reading stored in this object, and result in
          registered listeners being called.