def _reindex(
        self,
        indexers: Mapping[Any, Any] | None = None,
        method: str | None = None,
        tolerance: int | float | Iterable[int | float] | None = None,
        copy: bool = True,
        fill_value: Any = xrdtypes.NA,
        sparse: bool = False,
        **indexers_kwargs: Any,
    ) -> Self:
        """
        Same as reindex but supports sparse option.
        """
        indexers = utils.either_dict_or_kwargs(indexers, indexers_kwargs, "reindex")
        return alignment.reindex(
            self,
            indexers=indexers,
            method=method,
            tolerance=tolerance,
            copy=copy,
            fill_value=fill_value,
            sparse=sparse,
        )

        Same as reindex but supports sparse option.
        
xarray/core/dataset.py