package main

import "fmt"

func do(m1 *map[int]int) {
	(*m1)[0] = 0

	*m1 = make(map[int]int)
	(*m1)[10] = 10
	fmt.Println("m1", *m1)
}

func main() {
	m := map[int]int{1: 21, 2: 56, 3: 45}

	fmt.Println("m", m)
	do(&m)
	fmt.Println("m", m)
}