code: func (s *SeriesLong) Iter() *IterLong {
  	s.Lock()
  	w := s.bw.clone()
  	s.Unlock()
  
  	finishV2(w)
  	iter, _ := bstreamIteratorLong(s.T0, w)
  	return iter
  }
docs: // IterLong lets you iterate over a series.  It is not concurrency-safe.