Candor.ExecutionResults.AppendError C# (CSharp) Method

        public void AppendError( string message )
        {
            if (message == null)
                return;

            success_ = false;
            messages_.Add(new ExecutionStep(ExecutionStepType.Error, message));
        }

 public virtual ActionResult Register(RegisterViewModel model, string returnUrl)
 {
     if (ModelState.IsValid)
     {
         var results = new ExecutionResults();
         var user = model.ToUser();
         var identity = UserManager.RegisterUser(user, UserSessionDurationType.Extended, Request.UserHostAddress, results);
         if (results.Success)
         {   //successful registration
             SecurityContextManager.CurrentUser = new UserPrincipal(identity);
             return RedirectToLocal(returnUrl);
         }
         //failed business layer
         results.AppendError("Failed to complete registration.");
         for (var e = 0; e < results.Messages.Count; e++)
         {
             ModelState.AddModelError(e.ToString(CultureInfo.InvariantCulture), results.Messages[e].Message);
         }
     }
     //failed data annotation validations
     model.Load();
     return View(model);
 }