static void Main() { ICurrencyObserver niki = new NikolayObserver(); ICurrencyObserver fxcm = new FXCMObserver(); CurrencyPair gbpusd = new GBPUSDCurrencyPair(1.5583M); gbpusd.Register(niki); gbpusd.Register(fxcm); CurrencyPair eurusd = new EURUSDCurrencyPair(1.1423M); eurusd.Register(fxcm); gbpusd.Price = 1.5580M; gbpusd.Price = 1.5560M; eurusd.Price = 1.1534M; }