///It conforms to the \ref concepts::Digraph "Digraph concept" with

   ///It conforms to the \ref concepts::Digraph "Digraph concept" with

   ///an important extra feature that its maps are real \ref

   ///an important extra feature that its maps are real \ref

   ///concepts::ReferenceMap "reference map"s.

   ///concepts::ReferenceMap "reference map"s.

   ///

   ///

   ///\sa concepts::Digraph.

   ///\sa concepts::Digraph.

   class SmartDigraph : public ExtendedSmartDigraphBase {

   class SmartDigraph : public ExtendedSmartDigraphBase {

   public:

   public:

     typedef ExtendedSmartDigraphBase Parent;

     typedef ExtendedSmartDigraphBase Parent;