Able to read edge from undirected edgeset
Graph reader and graph writer can resolve items by id.

It makes possible:

GraphReader<Graph> reader(std::cin, graph);

reader.readNodeMap....

NewEdgeSetAdaptor<Graph> edgeset(graph);
UndirEdgeSetReader<Graph> unir_edgeset_reader(reader, edgeset, reader);

reader.run();

It reads the graph and an additional edgeset in to the edgeset.

 c LEMON max flow problem

 p max 7 9

 n 1 s

 n 7 t

 a 1 2 3

 a 1 3 2

 a 1 4 1

 a 2 5 3

 a 3 5 2

 a 3 7 5

 a 3 6 3

 a 4 6 1

 a 5 7 2

 a 6 7 4