public async Task <IActionResult> MarkComplete(string userName, string assignmentId)
        {
            User user = await _userManager.FindByNameAsync(userName);

            AssignmentDTO assignment = _Assignment.GetAssignment(assignmentId);

            if (user == null)
            {
                return(NotFound());
            }
            if (assignment == null)
            {
                return(NotFound());
            }
            _UserAssignment.MarkAsComplete(assignment, user);
            string id = assignment.Id;

            return(RedirectToAction("Index", "Home"));
        }