////   This file contains the C++ code from Program 4.12 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/pgm04_12.cpp//template <class T>void LinkedList<T>::Purge (){    while (head != 0)    {	ListElement<T>* const tmp = head;	head = head->next;	delete tmp;    }    tail = 0;}template <class T>LinkedList<T>::~LinkedList ()    { Purge (); }