docs: public static RoaringBitmap naive_and(Iterator<? extends RoaringBitmap> bitmaps) {
      if (!bitmaps.hasNext()) {
        return new RoaringBitmap();
      }
      RoaringBitmap answer = bitmaps.next().clone();
      while (bitmaps.hasNext()) {
        answer.and(bitmaps.next());
      }
      return answer;
    }