def _get_static_key(self, groups_of_interest, static_grouping_key):
        grouping_depth = len(groups_of_interest)
        group_index = grouping_depth - 1
        top_grouping = self.data[static_grouping_key]["groupings"]
        grouping = self._get_grouping(groups_of_interest, top_grouping, grouping_depth)

        keys = {group['label']: group['key'] for group in grouping}
        static_key = keys[groups_of_interest[group_index]]

        return static_key