anchor.diff:  
      ### Example
      ```
  -   > (* 2 (reset (+ 1 (shift k (continue k 5)))))
  +   > (* 2 (reset (+ 1 (shift k (k 5)))))
      out = 12
      ```"
     (let* [(cont (gensym))
  
positive.code:    .                   (lambda ()
     .                     (+ 1 (abort-to-prompt 'tag)))
     .                   (lambda (k)
     .                     (continue k 1)))
     out = 2
     ```"
    (let* [(k (cond
  
negative.code: 
     ### Example
     ```
     > (* 2 (reset (+ 1 (shift k (k 5)))))
     out = 12
     ```"
    `(abort-to-prompt ','reset-tag
  