while y: x, y = y, x % y return x

"""

"""
Save the code above as `gcd.py` and run it. It should print the correct results.

You can also run it through the interpreter, and it should execute properly.

A great feature of the interactive interpreter is that it allows you to test out your code as you write it.

The interpreter will also help you by showing you the error messages you get, if you make a mistake.

For example it has a problem with the Python code above: