public CreatedQuizDto CreateQuiz(CreateQuizDto createQuizDto, string userEmail)
        {
            var user = GetUserFromEmail(userEmail);

            createQuizDto.QuizOwnerId = user.Id;
            var playerIds = createQuizDto.Players.Select(dto => dto.Id);

            if (playerIds.Contains(createQuizDto.QuizOwnerId))
            {
                return(null);
            }
            var addedQuiz = _quizService.AddQuiz(createQuizDto);

            addedQuiz.QuizRoundDto = createQuizDto.Round;
            var addedRound = _roundService.AddRoundToQuiz(addedQuiz.QuizRoundDto, addedQuiz.Id);

            _roundService.InsertUsersIntoTheRoundUserPoints(addedRound.Id, createQuizDto.Players);
            return(new CreatedQuizDto {
                Id = addedQuiz.Id, Name = addedQuiz.Name, Date = addedQuiz.Date, PlayerInQuizDtos = createQuizDto.Players
            });
        }