private void B_Finish_Click(object sender, RoutedEventArgs e)
        {

            WorkWithDB.WriteCurrentSession();
            MainWindow w = new MainWindow();
            w.Show();
            Close();
        }
 private void B_Return_Click(object sender, RoutedEventArgs e)
 {
     MainWindow w = new MainWindow();
     w.Show();
     Close();
 }