public async Task <IActionResult> AddNewDeck([FromBody] NewDeckViewModel newDeck)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest());
            }

            var identity = User.GetIdentity();
            var deck     = await _deckService.AddNewDeck(identity, newDeck.Title, newDeck.Description);

            return(Ok(deck));
        }