How can I exit the window while press the Esc key

When I on the windows page I want to exit this window,how can I do it in code.

The following code do that as example.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace ?????.Views.Configuration
{
    /// <summary>
    /// Interaction logic for About.xaml
    /// </summary>
    public partial class About : Window
    {
        public About()
        {
            InitializeComponent();
            PreviewKeyDown += new KeyEventHandler(CloseOnEscape);
        }

        private void CloseOnEscape(object sender, KeyEventArgs e)
        {
            if (e.Key == System.Windows.Input.Key.Escape)
                Close();
        }
    }
}