# factorial_tutor.py
# Walker M. White (wmw2)
# October 13, 2015
"""Recursive implementation of factorial

This function should be copied into the Python Tutor.  That way you can
see how recursion affects the call stack."""

def factorial(n):
    """Returns: n!"""
    if n==0: # Base case
        return 1
    
    # Recursive case.
    return n*factorial(n-1)

factorial(0)
factorial(1)
factorial(4)