///\anchor writeGraph()

   ///

   /// Write a graph to the output.

   /// It is a helper function to write a graph to the given output

   /// stream. It gives back a GraphWriter object and this object

   /// can write more maps, labeled nodes and edges and attributes.

   /// \warning Do not forget to call the \c run() function.

   ///

   template<typename Graph>

   template <typename Graph>

   void writeGraph(std::ostream& os, const Graph &g) {

   GraphWriter<Graph> graphWriter(std::ostream& os, const Graph &g) {

     GraphWriter<Graph> writer(os, g);

     return GraphWriter<Graph>(os, g);

     IdMap<Graph, typename Graph::Node> nodeIdMap(g);

     writer.writeNodeMap("id", nodeIdMap);

     IdMap<Graph, typename Graph::Edge> edgeIdMap(g);

     writer.writeEdgeMap("id", edgeIdMap);

     writer.run();

   /// \brief Write a capacitated graph instance to the output.

   /// \brief Write a graph to the output.

   /// 

   ///

   /// Write a capacitated graph (graph+capacity on the

   /// It is a helper function to write a graph to the given output

   /// edges) to the output.

   /// file. It gives back a GraphWriter object and this object

   /// \param os The output stream.

   /// can write more maps, labeled nodes and edges and attributes.

   /// \warning Do not forget to call the \c run() function.

   ///

   /// \param fn The filename.

   /// \param capacity The capacity map.

   template <typename Graph>

   template<typename Graph, typename CapacityMap>

   GraphWriter<Graph> graphWriter(const std::string& fn, const Graph &g) {

   void writeGraph(std::ostream& os, const Graph &g, 

     return GraphWriter<Graph>(fn, g);

 		  const CapacityMap& capacity) {

     GraphWriter<Graph> writer(os, g);

     IdMap<Graph, typename Graph::Node> nodeIdMap(g);

     writer.writeNodeMap("id", nodeIdMap);

     IdMap<Graph, typename Graph::Edge> edgeIdMap(g);

     writer.writeEdgeMap("id", edgeIdMap);

     writer.writeEdgeMap("capacity", capacity);

     writer.run();

   }

   /// \brief Write a shortest path instance to the output.

   /// 

   /// Write a shortest path instance (graph+capacity on the

   /// edges+designated source) to the output.

   /// \param os The output stream.

   /// \param g The graph.

   /// \param capacity The capacity map.

   /// \param s The source node.

   template<typename Graph, typename CapacityMap>

   void writeGraph(std::ostream& os, const Graph &g, 

 		  const CapacityMap& capacity, const typename Graph::Node &s) {

     GraphWriter<Graph> writer(os, g);

     IdMap<Graph, typename Graph::Node> nodeIdMap(g);

     writer.writeNodeMap("id", nodeIdMap);

     IdMap<Graph, typename Graph::Edge> edgeIdMap(g);

     writer.writeEdgeMap("id", edgeIdMap);

     writer.writeEdgeMap("capacity", capacity);

     writer.writeNode("source", s);

     writer.run();

   }

   /// \brief Write a max flow instance to the output.

   ///

   /// Write a max flow instance (graph+capacity on the

   /// edges+designated source and target) to the output.

   ///

   /// \param os The output stream.

   /// \param g The graph.

   /// \param capacity The capacity map.

   /// \param s The source node.

   /// \param t The target node.

   template<typename Graph, typename CapacityMap>

   void writeGraph(std::ostream& os, const Graph &g, 

 		  const CapacityMap& capacity, const typename Graph::Node &s,

 		  const typename Graph::Node &t) {

     GraphWriter<Graph> writer(os, g);

     IdMap<Graph, typename Graph::Node> nodeIdMap(g);

     writer.writeNodeMap("id", nodeIdMap);

     IdMap<Graph, typename Graph::Edge> edgeIdMap(g);

     writer.writeEdgeMap("id", edgeIdMap);

     writer.writeEdgeMap("capacity", capacity);

     writer.writeNode("source", s);

     writer.writeNode("target", t);

     writer.run();

   }

   /// \brief Write a min cost flow instance to the output.

   ///

   /// Write a min cost flow instance (graph+capacity on the edges+cost

   /// function on the edges+designated source and target) to the output.

   ///

   /// \param os The output stream.

   /// \param g The graph.

   /// \param capacity The capacity map.

   /// \param s The source node.

   /// \param t The target node.

   /// \param cost The cost map.

   template<typename Graph, typename CapacityMap, typename CostMap>

   void writeGraph(std::ostream& os, const Graph &g, 

 		  const CapacityMap& capacity, const typename Graph::Node &s,

 		  const typename Graph::Node &t, const CostMap& cost) {

     GraphWriter<Graph> writer(os, g);

     IdMap<Graph, typename Graph::Node> nodeIdMap(g);

     writer.writeNodeMap("id", nodeIdMap);

     IdMap<Graph, typename Graph::Edge> edgeIdMap(g);

     writer.writeEdgeMap("id", edgeIdMap);

     writer.writeEdgeMap("capacity", capacity);

     writer.writeEdgeMap("cost", cost);

     writer.writeNode("source", s);

     writer.writeNode("target", t);

     writer.run();

   /// Write an undirected graph to the output.

   /// It is a helper function to write an undirected graph to the given output

   /// stream. It gives back an UndirGraphWriter object and this object

   /// can write more maps, labeled nodes and edges and attributes.

   /// \warning Do not forget to call the \c run() function.

   ///

   template<typename Graph>

   template <typename Graph>

   void writeUndirGraph(std::ostream& os, const Graph &g) {

   UndirGraphWriter<Graph> undirGraphWriter(std::ostream& os, const Graph &g) {

     UndirGraphWriter<Graph> writer(os, g);

     return UndirGraphWriter<Graph>(os, g);

     writer.run();

   /// \brief Write an undirected multigraph (undirected graph + capacity

   /// \brief Write an undirected graph to the output.

   /// map on the edges) to the output.

   ///

   ///

   /// It is a helper function to write an undirected graph to the given output

   /// Write an undirected multigraph (undirected graph + capacity

   /// file. It gives back an UndirGraphWriter object and this object

   /// map on the edges) to the output.

   /// can write more maps, labeled nodes, edges, undirected edges and 

   /// \param os The output stream.

   /// attributes.

   ///

   /// \warning Do not forget to call the \c run() function.

   ///

   /// \param fn The output file.

   /// \param capacity The capacity undirected map.

   template <typename Graph>

   template<typename Graph, typename CapacityMap>

   UndirGraphWriter<Graph> undirGraphWriter(const std::string& fn, 

   void writeUndirGraph(std::ostream& os, const Graph &g, 

 					   const Graph &g) {

 		       const CapacityMap& capacity) {

     return UndirGraphWriter<Graph>(fn, g);

     UndirGraphWriter<Graph> writer(os, g);

     writer.writeUndirEdgeMap("capacity", capacity);

     writer.run();