code: def contrast(self, value):
          
          assert(0x00 <= value <= 0xFF)
          self._contrast = value
          self._ws.ws2811_channel_t_brightness_set(self._channel, value)
          self._flush()
docs: Sets the LED intensity to the desired level, in the range 0-255.
  
          :param level: Desired contrast level in the range of 0-255.
          :type level: int