public void Undo()
{
switch (prevSpeed)
{
case CeilingFan.Speed.HIGH:
fan.High();
break;
case CeilingFan.Speed.MEDIUM:
fan.Medium();
break;
case CeilingFan.Speed.LOW:
fan.Low();
break;
case CeilingFan.Speed.OFF:
fan.Off();
break;
}
}
public void Execute()
{
fan.High();
}