private void btnUpdateTrainee_Click(object sender, RoutedEventArgs e)
        {
            var trainee = bl.getTraineeList().Find(x => x.ID == 317801157);//the id can be given in a textbox in the future

            bl.updateTrainee(trainee);
            try
            {
                bl.updateTrainee(Abigail);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }