def save(self, filename=None):
        filename = Path(filename) if filename is not None else self.filename
        with filename.open("w") as f:
            f.write(self.yaml)
def matchfn(self, f):
        # XXX: is_dir is set to True here for performance.
        # It should be set to whether "f" is actually a directory or not.
        return self._matcher.match_relative(f, True)