private void Poll()
        {
            isPolling = true;
            pollCountdownStopwatch.Reset();
            pollCountdownStopwatch.Start();
            long         value  = queue.LatestSequenceNumber + 1;
            List <long>  source = queue.SequenceNumbers.ToList();
            List <long?> excludeNotificationSequenceNumbers = source.Cast <long?>().ToList();
            GetNotificationsSinceSequenceRequest getNotificationsSinceSequenceRequest = new GetNotificationsSinceSequenceRequest();

            getNotificationsSinceSequenceRequest.SequenceNumber = value;
            getNotificationsSinceSequenceRequest.ExcludeNotificationSequenceNumbers = excludeNotificationSequenceNumbers;
            GetNotificationsSinceSequenceRequest request = getNotificationsSinceSequenceRequest;
            IWebCall <GetNotificationsSinceSequenceRequest, GetNotificationsResponse> webCall = webCallFactory.NotificationsSinceSequencePost(request);

            webCall.OnResponse += delegate(object sender, WebCallEventArgs <GetNotificationsResponse> e)
            {
                HandleGetNotificationsResponse(e.Response);
            };
            webCall.OnError += HandleGetNotificationsError;
            webCall.Execute();
        }