static void Main(string[] args)
{
ISubject subject = new Subject();
IObserver o1 = new Observer("Observer 1", false);
IObserver o2 = new Observer("Observer 2", true);
subject.subscribe(o1);
subject.subscribe(o2);
Thread.Sleep(TimeSpan.FromSeconds(30));
subject.unsubscribe(o2);
Thread.Sleep(TimeSpan.FromMinutes(10));
}