You forgot functools.lru_cache. I've found in some Python 2.7 projects you can speed things up with a hacky dictionary-cache, but the proper functools.lru_cache

You forgot functools.lru_cache. I've found in some Python 2.7 projects you can speed things up with a hacky dictionary-cache, but the proper functools.lru_cache gives better results and is far more flexible.