// Follows the path starting on edge e and returns its length. If
// nodes is non-null, stores in it the nodes met along the path.
int retrieve_one_path(Edge *e, Path *path);
// Follows the path starting on edge e and returns its length. If
// nodes is non-null, stores in it the nodes met along the path.
int retrieve_one_path(Edge *e, Path *path);