////   This file contains the C# code from Program 9.14 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C#"//   by Bruno R. Preiss.////   Copyright (c) 2001--2002 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.brpreiss.com/books/opus6/programs/pgm09_14.txt//public class GeneralTree : AbstractTree{    protected object key;    protected int degree;    protected LinkedList list;    public GeneralTree(object key)    {	this.key = key;	degree = 0;	list = new LinkedList();    }    public override void Purge()    {	list.Purge();	degree = 0;    }    // ...}