memoize.py

from functools import wraps

def memoize(f):
    cache = {}
    kwargs_mark = object()

    @wraps(f)
    def memoized(*args, **kwargs):
        key = args + (kwargs_mark,) + tuple(sorted(kwargs.items()))
        try:
            return cache[key]
        except KeyError:
            result = cache[key] = f(*args, **kwargs)
            return result

    return memoized