docs: def _storage_purge_all(delete=False, verbosity=0):
      """Purge unreferenced storages."""
      orphaned_storages = Storage.objects.filter(data=None)
  
      if verbosity >= 1:
          if orphaned_storages.exists():
              logger.info(__("Unreferenced storages ({}):", orphaned_storages.count()))
              for storage_id in orphaned_storages.values_list('id', flat=True):
                  logger.info(__("  {}", storage_id))
          else:
              logger.info("No unreferenced storages")
  
      if delete:
          orphaned_storages.delete()