docs: def _save_multi(data, file_name, sep=";"):
      """convenience function for storing data column-wise in a csv-file."""
      logger.debug("saving multi")
      with open(file_name, "w", newline='') as f:
          logger.debug(f"{file_name} opened")
          writer = csv.writer(f, delimiter=sep)
          try:
              writer.writerows(itertools.zip_longest(*data))
          except Exception as e:
              logger.info(f"Exception encountered in batch._save_multi: {e}")
              raise ExportFailed
          logger.debug("wrote rows using itertools in _save_multi")