def _item_sources(self) -> Iterable[Mapping[Hashable, Any]]:
        """Places to look-up items for key-completion"""
        yield self.data_vars
        yield FilteredMapping(keys=self._coord_names, mapping=self.coords)

        # virtual coordinates
        yield FilteredMapping(keys=self.sizes, mapping=self)
Places to look-up items for key-completion
xarray/core/dataset.py