memoize.py

def memoize(f):
    """ Memoization decorator for a function taking one or more arguments. """
    class memodict(dict):
        def __getitem__(self, *key):
            return dict.__getitem__(self, key)

        def __missing__(self, key):
            ret = self[key] = f(*key)
            return ret

    return memodict().__getitem__