code: func (h *Holder) Indexes() []*Index {
  	h.mu.RLock()
  	a := make([]*Index, 0, len(h.indexes))
  	for _, index := range h.indexes {
  		a = append(a, index)
  	}
  	h.mu.RUnlock()
  
  	sort.Sort(indexSlice(a))
  	return a
  }
docs: // Indexes returns a list of all indexes in the holder.