def group_slices(self):
        """The list of group slices of the view, or None if the view is not
        grouped.
        """
        if not self._has_slices:
            return None

        return list(self._get_group_media_types().keys())
The list of group slices of the view, or None if the view is not
        grouped.
        
fiftyone/core/view.py