Path relative(const Path &path, const Path &base);
/// Returns the longest prefix shared by both paths.
Path common_ancestor(const Path &, const Path &);
/** Determines how many levels a path is below another. Returns -1 if path is
Path relative(const Path &path, const Path &base);
/// Returns the longest prefix shared by both paths.
Path common_ancestor(const Path &, const Path &);
/** Determines how many levels a path is below another. Returns -1 if path is