code: func BytesPrefix(prefix []byte) *Range {
  	var limit []byte
  	for i := len(prefix) - 1; i >= 0; i-- {
  		c := prefix[i]
  		if c < 0xff {
  			limit = make([]byte, i+1)
  			copy(limit, prefix)
  			limit[i] = c + 1
  			break
  		}
  	}
  	return &Range{prefix, limit}
  }
docs: // BytesPrefix returns key range that satisfy the given prefix.
  // This only applicable for the standard 'bytes comparer'.