package main

import "fmt"

func message() string {

  m := ""
  arr := [4]int{1, 2, 3, 4}

  for i := 0; i < len(arr); i++ {
    arr[i] *= arr[i]
    m += fmt.Sprintf("%v: %v\n", i, arr[i])
  }

  return m

}

func main() {

  fmt.Print(message())

}