docs: public void decrease(final DeviceControllerChannel channel, final int steps)
  			throws IOException {
  
  		if (channel == null) {
  			throw new RuntimeException("null-channel is not allowed. For devices "
  					+ "knowing just one wiper Channel.A is mandatory for "
  					+ "parameter 'channel'");
  		}
  
  		// decrease only works on volatile-wiper
  		byte memAddr = channel.getVolatileMemoryAddress();
  
  		increaseOrDecrease(memAddr, false, steps);
  
  	}