public async Task Post(SCheckModel model)
        {
            IdentityUser me = await _userManager.FindByNameAsync(User.Identity.Name);

            Subscription sub = new Subscription
            {
                NoteFileId   = model.fileId,
                SubscriberId = me.Id,
            };

            _db.Subscription.Add(sub);
            await _db.SaveChangesAsync();
        }
        public async Task Post(SCheckModel model)
        {
            IdentityUser me = await _userManager.FindByNameAsync(User.Identity.Name);

            Sequencer tracker = new Sequencer
            {
                Active     = true,
                NoteFileId = model.fileId,
                LastTime   = DateTime.Now.ToUniversalTime(),
                UserId     = me.Id,
                Ordinal    = 0,
                StartTime  = DateTime.Now.ToUniversalTime()
            };

            _db.Sequencer.Add(tracker);
            await _db.SaveChangesAsync();
        }