public async Task <ActionResult> CreateSubscription()
        {
            string baseUrl = $"{Request.Url.Scheme}://{Request.Url.Authority}";

            try
            {
                var subscription = await SubscriptionHelper.CreateSubscription(baseUrl);

                SubscriptionViewModel viewModel = new SubscriptionViewModel()
                {
                    Subscription = subscription
                };

                return(View("Subscription", viewModel));
            }
            catch (Exception e)
            {
                ViewBag.Message = BuildErrorMessage(e);
                return(View("Error", e));
            }
        }