def memoize(obj):
    """
    Memoize objects to trade memory for execution speed

    Use a limited size cache to store the value, which takes into account
    The calling args and kwargs

    See https://wiki.python.org/moin/PythonDecoratorLibrary#Memoize
    """
    cache = obj.cache = {}

    @functools.wraps(obj)
    def memoizer(*args, **kwargs):
        key = str(args) + str(kwargs)
        if key not in cache:
            cache[key] = obj(*args, **kwargs)
        # only keep the most recent 100 entries
        if len(cache) > 100:
            cache.popitem(last=False)
        return cache[key]
    return memoizer