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)))<EOL>pandas_data_frame = temporal_network(gtfs, start_time_ut=start_time_ut, end_time_ut=end_time_ut)<EOL>pandas_data_frame.to_csv(output_filename, encoding='<STR_LIT:utf-8>', index=False)<EOL>
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)