code: def write_temporal_network(gtfs, output_filename, start_time_ut=None, end_time_ut=None):
      
      util.makedirs(os.path.dirname(os.path.abspath(output_filename)))
      pandas_data_frame = temporal_network(gtfs, start_time_ut=start_time_ut, end_time_ut=end_time_ut)
      pandas_data_frame.to_csv(output_filename, encoding='utf-8', index=False)
docs: Parameters
      ----------
      gtfs : gtfspy.GTFS
      output_filename : str
          path to the directory where to store the extracts
      start_time_ut: int | None
          start time of the extract in unixtime (seconds after epoch)
      end_time_ut: int | None
          end time of the extract in unixtime (seconds after epoch)