<DIRECTED RANT>

1. next and last are keywords, not functions. You cannot redefine their behavior. If they were functions, you'd be able to do so.
2. The question was concerning the capabilities of next and last when the scope had changed, especially concerning nested function calls. I would assume that, given the nature of the question, that the questioner knew how to use next and last.

</DIRECTED RANT>

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.