///only in the concept class.

   ///only in the concept class.

   ///

   ///

   ///\sa concepts::Digraph

   ///\sa concepts::Digraph

   class ListDigraph : public ExtendedListDigraphBase {

   class ListDigraph : public ExtendedListDigraphBase {

   private:

   private:

     ///ListDigraph is \e not copy constructible. Use copyDigraph() instead.

     ///ListDigraph is \e not copy constructible. Use copyDigraph() instead.

     ///ListDigraph is \e not copy constructible. Use copyDigraph() instead.

     ///ListDigraph is \e not copy constructible. Use copyDigraph() instead.

     ///

     ///

     ///Assignment of ListDigraph to another one is \e not allowed.

     ///Assignment of ListDigraph to another one is \e not allowed.

     ///Use copyDigraph() instead.

     ///Use copyDigraph() instead.

     void operator=(const ListDigraph &) {}

     void operator=(const ListDigraph &) {}

   public:

   public:

     /// Constructor

     /// Constructor

     /// Constructor.

     /// Constructor.

     ///

     ///

     int first_free_arc;

     int first_free_arc;

   public:

   public:

     class Node;

     class Node;

     class Arc;

     class Arc;

     class Edge;

     class Edge;

   ///only in the concept class.

   ///only in the concept class.

   ///

   ///

   ///\sa concepts::Graph

   ///\sa concepts::Graph

   class ListGraph : public ExtendedListGraphBase {

   class ListGraph : public ExtendedListGraphBase {

   private:

   private:

     ///ListGraph is \e not copy constructible. Use copyGraph() instead.

     ///ListGraph is \e not copy constructible. Use copyGraph() instead.

     ///ListGraph is \e not copy constructible. Use copyGraph() instead.

     ///ListGraph is \e not copy constructible. Use copyGraph() instead.

     ///

     ///

     /// Constructor

     /// Constructor

     /// Constructor.

     /// Constructor.

     ///

     ///

     ListGraph() {}

     ListGraph() {}

     typedef Parent::OutArcIt IncEdgeIt;

     typedef Parent::OutArcIt IncEdgeIt;

     /// \brief Add a new node to the graph.

     /// \brief Add a new node to the graph.

     ///

     ///