////   This file contains the C# code from Program 2.3 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/pgm02_03.txt//public class Example{    public static int Factorial(int n)    {	if (n == 0)	    return 1;	else	    return n * Factorial(n - 1);    }}