static void Main()
{
var clock = new CountdownClock();
var bath = new Bathroom();
var microwave = new Microwave();
bath.Register(clock);
microwave.Register(clock);
Console.WriteLine("The countdown has begun!");
clock.ImitationCountdownClock(5);
bath.Unregister(clock);
clock.ImitationCountdownClock(2);
Console.ReadKey();
}