docs: def write_geoff(discoursegraph, output_file):
      """
      converts a DiscourseDocumentGraph into a Geoff file and
      writes it to the given file (or file path).
      """
      if isinstance(output_file, str):
          with open(output_file, 'w') as outfile:
              outfile.write(convert_to_geoff(discoursegraph))
      else:  # output_file is a file object
          output_file.write(convert_to_geoff(discoursegraph))