public async Task <IActionResult> RemoveListFromGroup(int Id, int SpellingGroupId)
        {
            ListGroupAllocation allocation = await _context.ListGroupAllocations.SingleOrDefaultAsync(a => a.SpellingListId == Id && a.SpellingGroupId == SpellingGroupId);

            _context.ListGroupAllocations.Remove(allocation);

            await _context.SaveChangesAsync();

            return(RedirectToAction("AssignLists", new { SpellingGroupId = SpellingGroupId }));
        }
        public async Task <IActionResult> AddListToGroup(int Id, int SpellingGroupId)
        {
            ListGroupAllocation allocation = new ListGroupAllocation()
            {
                SpellingListId  = Id,
                SpellingGroupId = SpellingGroupId
            };

            await _context.ListGroupAllocations.AddAsync(allocation);

            await _context.SaveChangesAsync();

            return(RedirectToAction("AssignLists", new { SpellingGroupId = SpellingGroupId }));
        }