code: func (s *GlobalStore) keyNodeIndex(key []byte, addr common.Address) (index int, found bool) {
  	k := string(key)
  	l := len(s.keyNodes[k])
  	index = sort.Search(l, func(i int) bool {
  		return bytes.Compare(s.keyNodes[k][i][:], addr[:]) >= 0
  	})
  	found = index < l && s.keyNodes[k][index] == addr
  	return index, found
  }
docs: // keyNodeIndex returns the index of a node address in keyNodes slice.