/// If the graph is directed, the algorithm consider it to be 

   /// If the graph is directed, the algorithm consider it to be 

   /// undirected by disregarding the direction of the edges.

   /// undirected by disregarding the direction of the edges.

   ///

   ///

   /// \param in This object is used to describe the edge costs. It can be one

   /// \param in This object is used to describe the edge costs. It can be one

   /// of the following choices.

   /// of the following choices.

   /// - An STL compatible 'Forward Container' with

   /// - An STL compatible 'Forward Container' with

   /// <tt>std::pair<GR::UEdge,X></tt> or

   /// <tt>std::pair<GR::UEdge,X></tt> or

   /// <tt>std::pair<GR::Edge,X></tt> as its <tt>value_type</tt>, where

   /// <tt>std::pair<GR::Edge,X></tt> as its <tt>value_type</tt>, where

   /// \c X is the type of the costs. The pairs indicates the edges

   /// \c X is the type of the costs. The pairs indicates the edges

   /// along with the assigned cost. <em>They must be in a

   /// along with the assigned cost. <em>They must be in a