docs: def writelines_nl(fileobj: TextIO, lines: Iterable[str]) -> None:
      """
      Writes lines, plus terminating newline characters, to the file.
  
      (Since :func:`fileobj.writelines` doesn't add newlines...
      http://stackoverflow.com/questions/13730107/writelines-writes-lines-without-newline-just-fills-the-file)
      """  # noqa
      fileobj.write('\n'.join(lines) + '\n')