private void Chemistry_Button_Click(object sender, RoutedEventArgs e)
        {
            //chaplist.Clear();
            //  List<Chapter> chaps = subjlist[1].chapters;
            chaplist = new List <Chapter>(subjlist[1].Chapters);
            //chaplist.AddRange(subjlist[1].chapters);
            UIChapter uIChapter = new UIChapter(chaplist);

            Switcher.Switch(uIChapter);
        }
        private void Bio_Button_Click(object sender, RoutedEventArgs e)

        {
            // chaplist.Clear();

            //Subject sub = MetaData.mda.level.subjects[2];
            // List<Chapter> chaps =  subjlist[2].chapters;

            chaplist = new List <Chapter>(subjlist[2].Chapters);
            // chaplist.AddRange(subjlist[2].chapters);
            // MessageBox.Show(chaplist.Count().ToString());
            // MessageBox.Show();


            UIChapter uIChapter = new UIChapter(chaplist);

            Switcher.Switch(uIChapter);
        }