AI_Project_3.MainPage.AddtoClassesTaken_Click C# (CSharp) Method

        private void AddtoClassesTaken_Click(object sender, RoutedEventArgs e)
        {
            int selectedItem = this.AllClasses.SelectedIndex;
            if (selectedItem >= 0)
            {
                Class c = majorinit.listOfAllClasses.ElementAt(selectedItem);
                if (!majorinit.listOfClassesTaken.Contains(c))
                {
                    //The 'if' above checks for duplicates, below, we add it to the list, and change the class status to 'completed', then update
                    c.Status = ClassStatus.Completed;
                    majorinit.listOfClassesTaken.Add(c);
                    this.TakenClasses.ItemsSource = majorinit.listOfClassesTaken;
                }
            }
        }