anchor.diff:  (defun make-env ()
     '())
  +
  +(defun env-frame-empty-p (env)
  +  (null env))
   
   (defun env-first-frame (env)
     (car env))
  
positive.code:   (if (symbolp (cadr exp))
        (caddr exp)
        (make-lambda (cdadr exp)
  		   (caddr exp))))
  
  (defun make-lambda (parameters body)
    (format t "make-lamba parameters: ~a~%" parameters)
  
negative.code:   (rplaca frame (cons var (frame-vars frame)))
    (rplacd frame (cons val (frame-vals frame)))
    'ok)
  
  (defun frame-get (frame var)
    (labels ((iter (vars vals)
  