Factorial sketch(python 3)

[KingArthur526]

I am a fairly new python student, so please excuse any errors.
I am having trouble coming up with the correct output for this sketch i got from a friend. Could you please point out what's wrong and how to correct it?
For example, if i enter Factorial(16), i get 16 as the output.
But if i enter Factorial(4) i get 7 as the output.
This is the sketch:

n=7
def factorial(n):
    if n<0:
        n*=-1
        if (n==0):
            return 0
        f= 1
        while n>1:
            f*=n
            n-=1
            return f