Greatest Common Divisor using Recursion in Python source: http://code.activestate.com/recipes/578421-greatest-common-divisor-using-recursion-in-python/

gcd.py

import sys


def gcd(a, b):
    t = b
    b = a % b
    if b == 0:
        return t
    else:
        return gcd(t, b)


def main(argv):
    if (len(sys.argv) != 3):
        sys.exit('Usage: gcd.py <a> <b>')

    print abs(gcd(int(sys.argv[1]), int(sys.argv[2])))

if __name__ == "__main__":
    main(sys.argv[1:])