Historical note: at MIT this usage has traditionally been traced to the programming language MAD (Michigan Algorithm Decoder), an Algol-58-like language that was the most common choice among mainstream (non-hacker) users at MIT in the mid-60s. It inherited from Algol-58 a control structure FOR VALUES OF X = 3, 7, 99 DO ... that would repeat the indicated instructions for each value in the list (unlike the usual FOR that only works for arithmetic sequences of values). MAD is long extinct, but similar for-constructs still flourish (e.g., in Unix's shell languages).

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