以下func 输出结果为10的是？
func test1(x int) int { defer func() { x = 9 }() x = 10 return x }
func test2() (x int) { defer func() { x = 9 }() x = 10 return x }
func test3() (x int) { defer func() { x = 10 }() defer func() { x = 9 }() return x }
func test4() (x int) { defer func() { x = 9 }() defer func() { x = 10 }() return x }
