code: func IndentBytes(b, prefix []byte) []byte {
  	var res []byte
  	bol := true
  	for _, c := range b {
  		if bol && c != '\n' {
  			res = append(res, prefix...)
  		}
  		res = append(res, c)
  		bol = c == '\n'
  	}
  	return res
  }
docs: // IndentBytes inserts prefix at the beginning of each non-empty line of b.
  // The end-of-line marker is NL.