code: func writeLine(buf *bytes.Buffer, words ...string) {
  	// We avoid strings.Join for performance reasons.
  	for i := range words {
  		buf.WriteString(words[i])
  		if i < len(words)-1 {
  			buf.WriteByte(' ')
  		} else {
  			buf.WriteByte('\n')
  		}
  	}
  }
docs: // Join all words with spaces, terminate with newline and write to buff.