You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: functions.go
    path of file: ./repos/Mastering_Go_ZH_CN/eBook/examples/chapter6
    
    the code of the file until where you have to start completion: package main

import (
    "fmt"
    "os"
    "strconv"
)

func doubleSquare(x int) (int, int) {
    return x * 2, x * x
}

func main() {
    arguments := os.Args
    if len(arguments) != 2 {
        fmt.Println("The program needs 1 argument!")
        return
    }
    y, err := strconv.Atoi(arguments[1])
    if err != nil {
        fmt.Println(err)
        return
	}
	
    square := func(s
    
func main() {
    arguments := os.Args
    if len(arguments) != 2 {
        fmt.Println("The program needs 1 argument!")
        return
    }
    y, err := strconv.Atoi(arguments[1])
    if err != nil {
        fmt.Println(err)
        return
	}
	
    square := func(s int) int {
        return s * s
    }
    fmt.Println("The squre of", y, "is", square(y))

    double := func(s int) int {
        return s + s
    }
	fmt.Println("The double of", y, "is", double(y))
	
    fmt.Println(doubleSquare(y))
    d, s := doubleSquare(y)
    fmt.Println(d, s)
}