def open_groups_as_dict(
        self,
        filename_or_obj: str | os.PathLike[Any] | ReadBuffer | AbstractDataStore,
        *,
        drop_variables: str | Iterable[str] | None = None,
    ) -> dict[str, Dataset]:
        """
        Opens a dictionary mapping from group names to Datasets.

        Called by :py:func:`~xarray.open_groups`.
        This function exists to provide a universal way to open all groups in a file,
        before applying any additional consistency checks or requirements necessary
        to create a `DataTree` object (typically done using :py:meth:`~xarray.DataTree.from_dict`).
        """

        raise NotImplementedError()

        Opens a dictionary mapping from group names to Datasets.

        Called by :py:func:`~xarray.open_groups`.
        This function exists to provide a universal way to open all groups in a file,
        before applying any additional consistency checks or requirements necessary
        to create a `DataTree` object (typically done using :py:meth:`~xarray.DataTree.from_dict`).
        
xarray/backends/common.py