async *zscanIterator(key, options) {
    let cursor = "0";
    let items;
    do {
      [cursor, items] = await this.zscan(key, cursor, options);
      for (const item of items) {
        yield item;
      }
    } while (cursor !== "0");
  }
Same as `zscan` but returns an AsyncIterator to allow iteration via `for await`.