@Override
	public void undo() {
		
		if (prevSpeed == CeilingFan.HIGH)
			fan.high();
		else if (prevSpeed == CeilingFan.MEDIUM)
			fan.medium();
		else if (prevSpeed == CeilingFan.LOW)
			fan.low();
		else if (prevSpeed == CeilingFan.OFF)
			fan.off();
	}