static void Main(string[] args) { using (StockMarket market = new StockMarket()) { StockObserver msftObserver = new StockObserver("MSFT", 87.5m); msftObserver.Register(market); StockObserver fbObserver = new StockObserver("FB", 177m); fbObserver.Register(market); Console.ReadLine(); msftObserver.Deregister(); fbObserver.Deregister(); } }