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 json_usage(root):
    root = os.path.abspath(root)
    result = [['Path', 'Parent', 'Usage']]
    result.extend(entry for entry in usage_iter(root))
    return json.dumps(result)