public void Subscribe <T>(Action <T> eventHandlerTaskFactory)
        {
            eventHandlerTaskFactory.NullGuard();

            var subscription = new SyncSubscription <T>(eventHandlerTaskFactory);

            InternalSubscribe(subscription);
        }
        public void Unsubscribe <T>(Action <T> eventHandlerTaskFactory)
        {
            var subscription = new SyncSubscription <T>(eventHandlerTaskFactory);

            InternalUnsubscribe(subscription);
        }