（11）函数返回值

//单个返回值
func sum(a, b int) int {
    he := a + b
    return he
}

//预定义返回值名称
func sum2(a, b int) (he int) {
    he = a + b
    return
}

//预定义多个返回值名称
func sum3(a, b int) (he, cha, ji, shang int) {
    he = a + b
    cha = a - b
    ji = a * b
    shang = a / b

    return
}