/// \brief A bidirected graph template.

   ///

   ///\warning Graph wrappers are in even more experimental state than the other

   ///parts of the lib. Use them at you own risk.

   ///

   /// A bidirected graph template.

   /// Such a bidirected graph stores each pair of oppositely directed edges 

   /// ones in the memory, i.e. a directed graph of type 

   /// \c Graph is used for that.

   /// As the oppositely directed edges are logically different ones 

   /// the maps are able to attach different values for them.

   /// \ingroup graphs

   template<typename Graph>

   class BidirGraph : public BidirGraphWrapper<Graph> {

   public:

     typedef UndirGraphWrapper<Graph> Parent;

   protected:

     Graph gr;

   public:

     BidirGraph() : BidirGraphWrapper<Graph>() { 

       Parent::setGraph(gr); 

     }

     //    KEEP_MAPS(Parent, BidirGraph);

   };