////   This file contains the C# code from Program 5.2 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/pgm05_02.txt//public abstract class ComparableObject : IComparable{    public static bool operator ==(ComparableObject c, object o)    {	if ((object)c == null || (object)o == null)	    return (object)c == (object)o;	else	    return c.Compare(o) == 0;    }    public static bool operator !=(ComparableObject c, object o)    {	if ((object)c == null || (object)o == null)	    return (object)c != (object)o;	else	    return c.Compare(o) != 0;    }    public static bool operator <(ComparableObject c, object o)	{ return c.Compare(o) < 0; }    public static bool operator >(ComparableObject c, object o)	{ return c.Compare(o) > 0; }    public static bool operator <=(ComparableObject c, object o)	{ return c.Compare(o) <= 0; }    public static bool operator >=(ComparableObject c, object o)	{ return c.Compare(o) >= 0; }    // ...}