def _migration_index() -> dict[str, list[Callable[[_CHECKPOINT], _CHECKPOINT]]]:
    """Migration functions returned here will get executed in the order they are listed."""
    return {
        "0.10.0": [_migrate_model_checkpoint_early_stopping],
        "1.6.0": [_migrate_loop_global_step_to_progress_tracking, _migrate_loop_current_epoch_to_progress_tracking],
        "1.6.5": [_migrate_loop_batches_that_stepped],
        "1.9.0": [_migrate_model_checkpoint_save_on_train_epoch_end_default],
        "2.0.0": [
            _drop_apex_amp_state,
            _migrate_loop_structure_after_tbptt_removal,
            _migrate_loop_structure_after_optimizer_loop_removal,
            _migrate_loop_structure_after_dataloader_loop_removal,
        ],
    }
Migration functions returned here will get executed in the order they are listed.
src/lightning/pytorch/utilities/migration/migration.py