code: def _load_metadata(self):
          
          if self._schema is None:
              self._schema = self._get_schema()
              self.datashape = self._schema.datashape
              self.dtype = self._schema.dtype
              self.shape = self._schema.shape
              self.npartitions = self._schema.npartitions
              self.metadata.update(self._schema.extra_metadata)
docs: load metadata only if needed