<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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")