anchor.diff:  (defun walk-lambda-list (lambda-list parent env &key allow-specializers)
     (flet ((extend-env (argument)
                    (unless (typep argument 'allow-other-keys-function-argument-form)
  -                   (setf env (register env :let (name argument) argument)))))
  +                   (extend env :let (name argument) argument))))
       (let ((state :required)
             (arguments '()))
         (dolist (argument lambda-list)
  
positive.code:       (loop
           for part on (body tagbody)
           if (go-tag-p (car part))
             do (setf env (register env :tag (car part) (cdr part))))
        (loop
           for part on (body tagbody)
           if (go-tag-p (car part))
  
negative.code:                                  (second form)))
      (dolist* ((var . value) (binds let))
        (declare (ignore value))
        (extend env :let var :dummy))
      (multiple-value-setf ((body let) nil (declares let)) (walk-implict-progn let (cddr form) env :declare t))))
  
  (defclass let*-form (variable-binding-form)
  