def make_sorted_indices(
        self, strategy: "SupervisedTemplate", data: AvalancheDataset
    ) -> List[int]:
        """
        Should return the sorted list of indices to keep as exemplars.

        The last indices will be the first to be removed when cutoff memory.
        """
        ...

        Should return the sorted list of indices to keep as exemplars.

        The last indices will be the first to be removed when cutoff memory.
        
avalanche/training/storage_policy.py