def METHOD_NAME(self, all_res, *args, **kwargs):
    _ = args, kwargs
    if any_action_failed(all_res):
        raise IOError('Could not download files:', all_res)
    images = np.concatenate([all_res[0], all_res[2]])
    labels = np.concatenate([all_res[1], all_res[3]])
    preloaded = images, labels
    train_len, test_len = len(all_res[0]), len(all_res[2])
    index, train_index, test_index = self._infer_train_test_index(train_len, test_len)
    return preloaded, index, train_index, test_index