async function purge() {
  const deleteBeforeDate = new Date(new Date().getTime() - DAYS_TO_KEEP * 24 * 60 * 60 * 1000);
  logger.info(`Deleting all messages created before = ${deleteBeforeDate}`);
  await db.Message.destroy({
    where: {
      created_at: {
        [Op.lte]: deleteBeforeDate,
      },
    },
  });
  logger.info('Messages purged!');
}
@public
@description Purge.
@returns {Promise} Resolve.
@example
gladys.message.purge();