/// A wrapper for forgetting the orientation of a graph.

   /// A wrapper for forgetting the orientation of a graph.

   /// A wrapper for getting an undirected graph by forgetting

   /// A wrapper for getting an undirected graph by forgetting

   /// the orientation of a directed one.

   /// the orientation of a directed one.

   template<typename Graph>

   template<typename Graph>

   class UndirGraphWrapper : public GraphWrapper<Graph> {

   class UndirGraphWrapper : public GraphWrapper<Graph> {

   protected:

   protected:

     UndirGraphWrapper() : GraphWrapper<Graph>() { }

     UndirGraphWrapper() : GraphWrapper<Graph>() { }