Couple of questions/comments/nitpicks about the article:

- does the turnstile example in the article actually need a state machine? When you insert a coin it unlocks, when you push it locks. No need to remember the state you are in.

- in the data-fetching example, it says that in the "fetching" state it is not /accepting/ any clicks. But then shouldn't this be explicitly specified in the state machine, by having the click event loop back into the fetching state? I think it would be less error-prone and more systematic to account for all the events in all the states.