How to use the regionmask.defined_regions._ar6_pre_revisions.ar6_pre_revisions_cls function in regionmask

def __init__(self):
        super(ar6_pre_revisions_cls, self).__init__()

        self.__df = None
        self.__df_combined = None

        self._all = None
        self._land = None
        self._ocean = None
        self._separate_pacific = None

        self._name = "pre-revision version of 'IPCC AR6 WGI Reference Regions'"
        self._source = "Iturbide et al., 2020 (Earth Syst. Sci. Data)"

self._separate_pacific = from_geopandas(
                df,
                names="V2",
                abbrevs="V3",
                name=self._name + "(separate Pacific regions)",
                source=self._source,
            )

        return self._separate_pacific

    def __repr__(self):  # pragma: no cover
        return REPR


_ar6_pre_revisions = ar6_pre_revisions_cls()