Method _warn

xarray/core/utils.py:539–545

(self)

    __slots__ = ("mapping",)

    def _warn(self) -> None:
        emit_user_level_warning(
            "The return type of `Dataset.dims` will be changed to return a set of dimension names in future, "
            "in order to be more consistent with `DataArray.dims`. To access a mapping from dimension names to lengths, "
            "please use `Dataset.sizes`.",
            FutureWarning,
        )

    def __getitem__(self, key: K) -> V:
        self._warn()