code: def current_state_str(self):
          
          if self.sample_ok:
              msg = ''
              temperature = self._get_value_opc_attr('temperature')
              if temperature is not None:
                  msg += 'Temp: %s ºC, ' % temperature
              humidity = self._get_value_opc_attr('humidity')
              if humidity is not None:
                  msg += 'Humid: %s %%, ' % humidity
              pressure = self._get_value_opc_attr('pressure')
              if pressure is not None:
                  msg += 'Press: %s mb, ' % pressure
              light_level = self._get_value_opc_attr('light_level')
              if light_level is not None:
                  msg += 'Light: %s lux, ' % light_level
              return msg[:-2]
          else:
              return "Bad sample"
docs: Return string representation of the current state of the sensor.