@gen.coroutine
    def prepare(self):
        self._ensure_redis_client()
        super(RedisMixin, self).prepare()
Yields (fieldnum, text, docfreq, indexfreq) tuples for
dataset/ETHPy150Open gmr/tinman/tinman/handlers/mixins.py/RedisMixin.prepare--crossover with--dataset/ETHPy150Open dokipen/whoosh/src/whoosh/reading.py/IndexReader.__iter__