private void EvaluateConfidence(object sender, EmotionEventArgs e)
        {
            /* The quiz instance lives within this class (not ProblemPage.xaml.cs)
             * so increment the number of times emotion values have been analyzed
             * for the quiz class object.  This is not always 1:1 with the number
             * of answered problems because a bad picture may be taken with no results.
             */
            quiz.AddEmotionsForLastSolvedProblem(e.Anger, e.Contempt, e.Disgust,
                                                 e.Fear, e.Happiness, e.Neutral,
                                                 e.Sadness, e.Surprise);

            //If the last math problem has been solved, then the results screen
            //is being shown and we do not need to generate the last problem.
            if (MathProblems.Count != 0)
            {
                //Generate a new problem only if the user got the answer correct
                //but was not confident
                if (quiz.WasPreviousAnswerCorrect && !quiz.IsUserConfident(e))
                {
                    var newProblemQueue = quiz.GenerateMathProblems(1);
                    MathProblems.Enqueue(newProblemQueue.Dequeue());
                    quiz.NumberOfGeneratedProblems++;
                }
            }
            else
            {
                /* This means the results screen is showing, so raise event letting
                 * the results screen know that the average confidence has been
                 * returned and calculated.
                 */
                ResultsScreenDataReady(this, new ConfidenceEventArgs(quiz.ConfidenceAverage));
            }
        }
        public void HintRequested(object sender, EventArgs e)
        {
            //Enqueue a new problem when user requests a hint
            var newProblemQueue = quiz.GenerateMathProblems(1);

            MathProblems.Enqueue(newProblemQueue.Dequeue());
            quiz.NumberOfGeneratedProblems++;
        }