Please use python 3.8:

Design a function called num_factors that takes an integer as an argument. The function returns the number of factors of the integer: For example: num_factors(12) returns 6, since there are 6 factors of 12 (1, 2, 3, 4, 6, and 12).

Important: The implementation of your function must include a call to the is_factor function

def is_factor(n1: int, n2: int) -> bool: return (n2 % n1 == 0)