The way Python does it is intuitive to someone coming from an imperative background. But someone coming from a functional background could easily fall into the

The way Python does it is intuitive to someone coming from an imperative background. But someone coming from a functional background could easily fall into the trap of reasoning with generators as lazy lists. To me, it's not obvious that map(fn, g) should have a side-effect on g. I'm not saying I agree with the guy, but to call it magic is misleading.