scala如何嵌套方法

def factorial(x: Int): Int = {    def fact(x: Int, accumulator: Int): Int = {      if (x <= 1) accumulator      else fact(x - 1, x * accumulator)    }      fact(x, 1) }
 println("Factorial of 2: " + factorial(2)) println("Factorial of 3: " + factorial(3))

Factorial of 2: 2Factorial of 3: 6