; Changes:
  * removed : 0
  * added : 1
  * swaps : 0
; * negated predicates: 0
; * swapped branches: 0
; * calls to id fun: 0
(letrec ((f (lambda (x)
              (letrec ((g (lambda (y)
                            (+ x y))))
                 (g 5)))))
   (<change>
      ()
      =)
   (= (f 0) 5))
 Changes:
 * negated predicates: 0
 * swapped branches: 0
 * calls to id fun: 0
  * removed : 0
  * added : 1
  * swaps : 0
(letrec ((f (lambda (x)
              (letrec ((g (lambda (y)
                            (+ x y))))
                 (g 5)))))
   (<change>
      ()
      =)
   (= (f 0) 5))