def METHOD_NAME(lang_file):
    """Closes a <lang>.json file created with _create_lang_file().
    This also writes the terminating left brace and newline.
    Args:
        lang_file: A file opened with _create_lang_file().
    Raises:
        IOError: An error occurred while writing to or closing the file.
    """
    lang_file.write('\n}\n')
    lang_file.close()