////   This file contains the C++ code from Program 5.18 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_18.cpp//class Association : public Object, public Ownership{protected:    Object* key;    Object* value;    int CompareTo (Object const&) const;public:    Association (Object&);    Association (Object&, Object&);    ~Association ();    Object& Key () const;    Object& Value () const;    HashValue Hash () const;    void Put (ostream&) const;};