static void Main(string[] args)
{
var stockObservable = new Observable <Stock>();
var microsoftObserver = new MicrosoftStockObserver();
microsoftObserver.Subscribe(stockObservable);
var googleObserver = new GoogleStockObserver();
googleObserver.Subscribe(stockObservable);
stockObservable.Subject = new Stock("Microsoft", 10);
microsoftObserver.Unsubscribe();
stockObservable.Subject = new Stock("Microsoft", 20);
stockObservable.Subject = new Stock("Microsoft", 30);
microsoftObserver.Subscribe(stockObservable);
stockObservable.Subject = new Stock("Microsoft", 40);
stockObservable.Subject = new Stock("Google", 60);
googleObserver.Unsubscribe();
stockObservable.Subject = new Stock("Google", 70);
stockObservable.Subject = new Stock("Google", 80);
googleObserver.Subscribe(stockObservable);
stockObservable.Subject = new Stock("Google", 90);
stockObservable.Error(new StockNotFoundException("Some error occured!"));
stockObservable.Completed();
Console.ReadLine();
}