Factorial By Recursion

Complete factorial(n: int) -> int so it returns n factorial by recursion. The base case is already written: factorial(0) is 1. Add the recursive case, which returns n multiplied by the factorial of one less, so that factorial(5) works out as 5 * 4 * 3 * 2 * 1. Do NOT write a main block or any top-level test code; the tests construct the calls. Input: one integer n, no prompt, which the tests read and pass to your function before printing the value it returns.