public void Unsubscribe(ClientObserver observer)
 {
     lock (_MyLock)
     {
         if (Subscribers.Contains(observer))
         {
             Subscribers.Remove(observer);
         }
     }
 }
 public void Subscribe(ClientObserver observer)
 {
     lock (_MyLock)
     {
         if (observer != null && !Subscribers.Contains(observer))
         {
             Subscribers.Add(observer);
         }
     }
 }