gistfile1.py

def santa(people):
    return dict(zip(people, reversed(people)))


def describe_santa():
    bob, george, judy = 'bob jones', 'george jetson', 'judy smith'

    def takes_lists_of_people():
        santa([bob, george])

    def pairs_people_with_eachother():
        pairs = santa([bob, george])
        assert pairs[bob] == george
        assert pairs[george] == bob

    def assigns_pairs_to_each_of_three_people():
        people = [bob, george, judy]
        pairs = santa(people)
        assert set(pairs.keys()) == set(pairs.values()) == set(people)