public Observable(IOBservable duck)
 {
     this.duck = duck;
 }
 public void update(IOBservable duck)
 {
     Console.WriteLine("OBSERVER - {0} just quacked!", duck.GetType().Name);
 }
 public void update(IOBservable duck)
 {
     Console.WriteLine("OBSERVER - {0} just quacked!", duck.GetType().Name);
 }
 public Observable(IOBservable duck)
 {
     this.duck = duck;
 }