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main's row is everything the program may touch

A program's main lists its requirements after $ like any other function, and that row is the most any code below it can ask for. This one says $ Console: it may print, and nothing else. No helper, however deep, and no library, however updated, can open a file, call the network, or read the clock behind its back, because a call that needs more than main grants does not compile. To give the program more, you widen one line, where a reviewer sees it. A row bounds what code asks for, not what a value you pass it already carries.

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