code: func shuffle(input []string) []string {
  	tmp := make([]string, len(input))
  	r := rand.New(rand.NewSource(time.Now().Unix()))
  	for i, j := range r.Perm(len(input)) {
  		tmp[i] = input[j]
  	}
  	return tmp
  }
docs: // shuffle list of input strings