////   This file contains the C++ code from Program 5.13 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm05_13.cpp//class Iterator{public:    virtual ~Iterator ();    virtual void Reset () = 0;    virtual bool IsDone () const = 0;    virtual Object& operator * () const = 0;    virtual void operator ++ () = 0;};