////   This file contains the C++ code from Program 11.12 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/pgm11_12.cpp//class BinomialTree : public GeneralTree{    void SwapContents (BinomialTree&);public:    BinomialTree (Object&);    void Add (BinomialTree&);    BinomialTree& Subtree (unsigned int) const;};