////   This file contains the C++ code from Program 10.4 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/pgm10_04.cpp//Object& BST::Find (Object const& object) const{    if (IsEmpty ())	return NullObject::Instance ();    int const diff = object.Compare (*key);    if (diff == 0)	return *key;    else if (diff < 0)	return Left ().Find (object);    else	return Right ().Find (object);}Object& BST::FindMin () const{    if (IsEmpty ())	return NullObject::Instance ();    else if (Left ().IsEmpty ())	return *key;    else	return Left ().FindMin();}