def group_media_types(self):
        """A dict mapping group slices to media types, 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_media_types)
            # {'left': 'image', 'right': 'image', 'pcd': 'point-cloud'}
        """
        if self.media_type != fom.GROUP:
            return None

        return self._doc.group_media_types
A dict mapping group slices to media types, 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_media_types)
            # {'left': 'image', 'right': 'image', 'pcd': 'point-cloud'}
        
fiftyone/core/dataset.py