anchor.diff:    (let ((x 0)
           (y 0))
       (double-setf-BAD x y (+ x 100))
  -    (assert-equal x ____)
  -    (assert-equal y ____)))
  +    (assert-equal x 100)
  +    (assert-equal y 200)))
   
   ;; sets sym1 and sym2 to val
   (defmacro double-setf-SAFER (sym1 sym2 val)
  
positive.code:    (repeat-2 (do-something arg1 arg2)))
  
    (assert-expands
     ____
     (repeat-2 (setf x (+ 1 x)))))
  
  
  
negative.code: (defmacro log-form (form)
    "records the body form to the list *log* and then evalues the body normally"
    `(let ((retval ,form))
       (push ',form *log*) ;; ',form save the argument as is passed to macro¹
       retval))
  ;; ¹: (log-form (+ 1 2)) ;; *log* => ((+ 1 2))
  ;; so ',form <=> '(+ 1 2)
  
  (define-test test-basic-log-form
    "illustrates how the basic log-form macro above works"
  