System Xml Linq C# by API

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Xml;
using System.Xml.Linq;
public class MainClass {
    public static void Main() {
        XElement firstParticipant;
        XDocument xDocument = new XDocument(
          new XElement("Books", firstParticipant =
            new XElement("Book",
              new XAttribute("type", "Author"),
              new XElement("FirstName", "J"),
              new XElement("LastName", "R")),
            new XElement("Book",
              new XAttribute("type", "Author"),
              new XElement("FirstName", "E"),
              new XElement("LastName", "B"))));
        Console.WriteLine(xDocument);
        firstParticipant.Changing += new EventHandler(MyChangingEventHandler);
        firstParticipant.Changed += new EventHandler(MyChangedEventHandler);
        xDocument.Changed += new EventHandler(DocumentChangedHandler);
    }
    public static void MyChangingEventHandler(object sender, XObjectChangeEventArgs cea)
    {
      Console.WriteLine("Type of object changing: {0}, Type of change: {1}",
        sender.GetType().Name, cea.ObjectChange);
    }
    public static void MyChangedEventHandler(object sender, XObjectChangeEventArgs cea)
    {
      Console.WriteLine("Type of object changed: {0}, Type of change: {1}",
        sender.GetType().Name, cea.ObjectChange);
    }
    public static void DocumentChangedHandler(object sender, XObjectChangeEventArgs cea)
    {
      Console.WriteLine("Doc: Type of object changed: {0}, Type of change: {1}{2}",
        sender.GetType().Name, cea.ObjectChange, System.Environment.NewLine);
    }    
}