in labs/vstsextend/launchdarkly/codesnippet/AccountController.cs [325:356]
        public async Task<IActionResult> SendCode(SendCodeViewModel model)
        {
            if (!ModelState.IsValid)
            {
                return View();
            }
            var user = await SignInManager.GetTwoFactorAuthenticationUserAsync();
            if (user == null)
            {
                return View("Error");
            }
            // Generate the token and send it
            var code = await UserManager.GenerateTwoFactorTokenAsync(user, model.SelectedProvider);
            if (string.IsNullOrWhiteSpace(code))
            {
                return View("Error");
            }
            var message = "Your security code is: " + code;
            if (model.SelectedProvider == "Email")
            {
                await MessageServices.SendEmailAsync(await UserManager.GetEmailAsync(user), "Security Code", message);
            }
            else if (model.SelectedProvider == "Phone")
            {
                await MessageServices.SendSmsAsync(await UserManager.GetPhoneNumberAsync(user), message);
            }
            return RedirectToAction("VerifyCode", new { Provider = model.SelectedProvider, ReturnUrl = model.ReturnUrl, RememberMe = model.RememberMe });
        }