/* The following code example is taken from the book * "C++ Templates - The Complete Guide" * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002 * * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */#include "coord.hpp"// concrete geometric object class Circle// - \bfseries not derived from any classclass Circle {  public:    void draw() const;    Coord center_of_gravity() const;    //...};// concrete geometric object class Line// - \bfseries not derived from any classclass Line {  public:    void draw() const;    Coord center_of_gravity() const;    //...};//...