////   This file contains the C++ code from Program 4.13 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/pgm04_13.cpp//template <class T>ListElement<T> const* LinkedList<T>::Head () const    { return head; }template <class T>ListElement<T> const* LinkedList<T>::Tail () const    { return tail; }template <class T>bool LinkedList<T>::IsEmpty () const    { return head == 0; }