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

        Examples::

            import fiftyone as fo
            import fiftyone.zoo as foz

            dataset = foz.load_zoo_dataset("quickstart-groups")

            print(dataset.group_slices)
            # ['left', 'right', 'pcd']
        """
        if self.media_type != fom.GROUP:
            return None

        return list(self._doc.group_media_types.keys())
The list of group slices of the dataset, or None if the dataset is
        not grouped.

        Examples::

            import fiftyone as fo
            import fiftyone.zoo as foz

            dataset = foz.load_zoo_dataset("quickstart-groups")

            print(dataset.group_slices)
            # ['left', 'right', 'pcd']
        
fiftyone/core/dataset.py