static void Main(string[] args)
{
Console.WriteLine("Observer Pattern");
IObserver obs1 = new ObserverType1("Jessie");
IObserver obs2 = new ObserverType2("Luke");
IObserver obs3 = new ObserverType1("Bo");
Subject sbj = new Subject();
sbj.Register(obs1);
sbj.Register(obs2);
sbj.Register(obs3);
sbj.Flag = 50;
sbj.UnRegister(obs1);
sbj.Flag = 100;
}