public static void Observer() { var fievSeconds = new TimeSpan(0, 0, 5); var pulseObservable = new TimePulseObservable(fievSeconds); Console.WriteLine("························ Initialize time pulse with 5 seconds"); var pulseWriter = new TimePulseWriter(); pulseObservable.Subscribe(pulseWriter); Console.WriteLine("························ Subscribed pulse writer"); var pulseBeeper = new TimePulseBeeper(); pulseObservable.Subscribe(pulseBeeper); Console.WriteLine("························ Subscribed pulse beeper"); Console.WriteLine("························ Unmute speakers and wait 5 seconds ..."); }