What is the factorial of an integer in Python?

[SubhanUllah]

def factorial(n):  
    if(n==0): 
        return(1) 
    else:  
        return(n*factorial(n-1)) 
Here is a recursive version of a function to calculate the factorial of any positive integer in Python. However, it doesn’t have input validation to make sure the input is actually an integer or actually a positive number. You can add that in yourself.