long estimatedSize = 0L;
    ImmutableList.Builder<Spliterator.OfDouble> splitrsBuilder =
        new ImmutableList.Builder<>(streams.length);
    for (DoubleStream stream : streams) {
      isParallel |= stream.isParallel();
      Spliterator.OfDouble splitr = stream.spliterator();
      splitrsBuilder.add(splitr);
      characteristics &= splitr.characteristics();