code: func (i *Index) Chunks(r *sam.Reference, beg, end int) ([]bgzf.Chunk, error) {
  	chunks, err := i.idx.Chunks(r.ID(), beg, end)
  	if err != nil {
  		return nil, err
  	}
  	if i.MergeStrategy == nil {
  		return index.Adjacent(chunks), nil
  	}
  	return i.MergeStrategy(chunks), nil
  }
docs: // Chunks returns a []bgzf.Chunk that corresponds to the given genomic interval.