memoize.py

def memoize(obj):
    """
    Usage:
    @memoize
    def my_func():
        ...
    """
    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)
        return cache[key]
    return memoizer