So, like context managers in Python, except you only have `__exit__` and not `__enter__`. What's missing from the article is the semantics when there is an err

So, like context managers in Python, except you only have `__exit__` and not `__enter__`. What's missing from the article is the semantics when there is an error. In Python, `__exit__` is always called (with the exception as param), but depending of if you return True or False, you reraise or not the exception. Anyway, it's a useful addition. While you can craft an API with this behavior in JS by accepting two callbacks, it's nice to have a standardized way to do it. Plus making it an official feature will encourage the pattern, which nurture the culture for better API.