def index_list(self):
    return self._ensure_current_batch().index_list
get callback
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/datastore/datastore_query.py/ResultsIterator.index_list--crossover with--dataset/ETHPy150Open EricssonResearch/calvin-base/calvin/runtime/north/storage.py/Storage.get_concat_iter_cb