def __repr__(self):
        return "<NamedRequirements({}{})>".format(
            self.name,
            ", filename='{}'".format(self.filename.name) if self.filename
            else "")
def rel(self, f):
        """Convert repo path back to path that is relative to cwd of matcher."""
        return util.pathto(self._root, self._cwd, f)