static void Main(string[] args)
{
Clock clock = new Clock(new TimeSpan(0, 0, 5));
TimeObserver tw1 = new TimeObserver("tw1");
TimeObserver tw2 = new TimeObserver("tw2");
TimeObserver tw3 = new TimeObserver("tw3");
clock.AddObserver(tw1);
clock.AddObserver(tw2);
clock.AddObserver(tw3);
clock.StartTimer();
clock.RemoveObserver(tw2);
Console.ReadLine();
}