如何在golang中访问嵌套的映射数据？

Here I have a variable which show me the result in the nested mapped data but I want to access the nested mapped data values. How I will try to get the nested mapped data in the below program:-

package main

import (
    "fmt"
)

func main() {
    var five []int
    var ten []int
    mp1 := make(map[string]interface{})

    for i := 0; i < 0; i++ {
        if i > 5 {
            five = append(five, i)
        }
        ten = append(ten, i)
        fmt.Println(i)
    }
    mp1["not_completed"] = five
    mp1["completed"] = ten

    mp3 := make(map[string]interface{})
    mp3["new_data"] = mp1

    fmt.Println(mp3)
    fmt.Println(mp3["new_data"])
}

This is the link of the go playground I want to access the values of the data mapped in "completed" and "not_completed" . Will anyone give some help to me to solve this.

for _, v := range mp3 {
    for _,v1:= range v.(map[string]interface{}){
    fmt.Println(v1)
    }
}

https://play.golang.org/p/9zt0Z2Z4lXe