private void DeleteAnswer()
        {
            if (SelectedAnswer == null)
            {
                return;
            }

            Question.AnswerSetValues.Remove(SelectedAnswer);
            AnswerSetValues.Remove(SelectedAnswer);
        }
        private void AddExistingAnswer()
        {
            if (SelectedExistingAnswer == null)
            {
                return;
            }
            if (Question.AnswerSetValues.Any(value => value.Value.Equals(SelectedExistingAnswer.Value)))
            {
                return;
            }

            Question.AnswerSetValues.Add(SelectedExistingAnswer);
            AnswerSetValues.Add(SelectedExistingAnswer);

            SelectedAnswer = SelectedExistingAnswer;
        }
        private void AddNewAnswer()
        {
            if (string.IsNullOrWhiteSpace(NewAnswerText))
            {
                return;
            }

            NewAnswerText = NewAnswerText.Trim();

            if (Question.AnswerSetValues.Any(value => value.Value.Equals(NewAnswerText)))
            {
                return;
            }

            var newAnswer = new AnswerSetValue {
                Value = NewAnswerText
            };

            Question.AnswerSetValues.Add(newAnswer);
            AnswerSetValues.Add(newAnswer);

            SelectedAnswer = newAnswer;
        }