anchor.diff:  
   (5am:test build-32
     (signals varjo-conditions:symbol-unidentified
  -    (varjo.tests::compile-vert () :450
  +    (compile-vert () :450
         (labels ((foo ((ffn (function (:int) :int)))
                    (funcall ffn y)))
           (let ((y 10))
  
positive.code: 
  (5am:test build-31
    (signals varjo-conditions:cross-scope-mutate
      (varjo.tests::compile-vert () :450
        (let* ((y 10)
               (fn (labels ((test ((x :int)) x))
                     #'test)))
  
negative.code: 
  (5am:test build-33
    (is (ast-stabalizes-p
         (compile-vert () :450
           (let ((fn (labels ((test ((x :int)) x))
                       #'test)))
             (labels ((foo ((ffn (function (:int) :int)))
  