code: func (i *Index) MergeChunks(s index.MergeStrategy) {
  	if s == nil {
  		return
  	}
  	for _, ref := range i.refs {
  		for b, bin := range ref.bins {
  			if !sort.IsSorted(byBeginOffset(bin.chunks)) {
  				sort.Sort(byBeginOffset(bin.chunks))
  			}
  			ref.bins[b].chunks = s(bin.chunks)
  			if !sort.IsSorted(byBeginOffset(bin.chunks)) {
  				sort.Sort(byBeginOffset(bin.chunks))
  			}
  		}
  	}
  }
docs: // MergeChunks applies the given MergeStrategy to all bins in the Index.