code: def brightness(self, brightness):
          
          if brightness < 0 or brightness > 1:
              raise ValueError("Brightness must be a percentage "
                               "represented as decimal 0-1.0")
          self._brightness = brightness
          cmd = self.command_set.brightness(brightness)
          self.send(cmd)
docs: Set the group brightness.
  
          :param brightness: Brightness in decimal percent (0.0-1.0).