GCD of two numbers in Python

[Arshali12]

I am trying to write a Python program to find the greatest common divisor of two numbers in Python. I have been following the algorithm described here, but I am having trouble getting it to work.

def gcd(a, b):
    while b != 0:
        a, b = b, a % b
    return a

When I run this code, I am getting an error:

Traceback (most recent call last):
  File "gcd.py", line 4, in <module>
    return a % b
ZeroDivisionError: division by zero

I am not sure what I am doing wrong. Can anyone help me?
Thanks