gistfile1.cs

        public void Test()
        {
            var notification = new NotificationManager();
            var handler = new ChatMessageHandler<WhisperMessage>();

            handler.Register((msg, sub) =>
            {
                if (msg.Content == null)
                {
                    sub.Unsubscribe(notification);
                }
            }, null);
            notification.Subscribe<WhisperMessage>(handler);
        }