Python Circular Imports

foo.py

import spam

def goodbye(name):
    print("Goodbye {0}".format(name))

if __name__ == '__main__':
    print(spam.abc)
    spam.greet('Dan')

spam.py

import foo

abc = '123'

def greet(name):
    print("Hello, {0}".format(name))

if __name__ == '__main__':
    foo.goodbye('Mary')