anchor.diff:                                       :parent labels
                                        :source (list* name arguments body))
            do (push (cons name lambda) (binds labels))
  -         do (setf env (register env :flet name lambda)))
  +         do (extend env :flet name lambda))
         (setf (binds labels) (nreverse (binds labels)))
         (loop
            for form in binds
  
positive.code:   (let ((walk-env '()))
      (when lexical-env
        (dolist (var (lexical-variables lexical-env))
          (setf walk-env (register walk-env :lexical-let var t)))
        (dolist (fun (lexical-functions lexical-env))
  	(setf walk-env (register walk-env :lexical-flet fun t))))
      walk-env))
  
  ;;;; This takes a Common Lisp form and transforms it into a tree of
  
negative.code: (defun walk-lambda-list (lambda-list parent env &key allow-specializers)
    (flet ((extend-env (argument)
                   (unless (typep argument 'allow-other-keys-function-argument-form)
                     (extend env :let (name argument) argument))))
      (let ((state :required)
            (arguments '()))
        (dolist (argument lambda-list)
  