docs: def close(self):
          """Close and delete instance."""
  
          # remove callbacks
          DatastoreLegacy.datastores[self.domain].remove(self)
  
          # delete data after the last instance is gone
          if self.release_storage and \
             not DatastoreLegacy.datastores[self.domain]:
              del DatastoreLegacy.store[self.domain]
  
          del self