anchor.diff:        (flet ((return-0 () (push 0 side-effects) 0)
                (return-3 () (push 3 side-effects) 3))
           (for (i (return-0) (return-3))
  -             (push i result)))
  +          (push i result)))
         (assert-equal '(0 1 2 3) (nreverse result))
         (assert-equal '(0 3) (nreverse side-effects)))))
  
positive.code:       (flet ((return-0 () (push 0 side-effects) 0)
               (return-3 () (push 3 side-effects) 3))
          (for (i (return-0) (return-3))
               (push i result)))
        (assert-equal ____ (nreverse result))
        (assert-equal ____ (nreverse side-effects)))))
  
  
negative.code:     (let ((limit 10)
            (result '()))
        (for (i 0 3)
          (push i result)
          (assert-equal ____ limit))
        (assert-equal ____ (nreverse result)))))
  
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