anchor.diff:    (lambda (env)
       (setf (getf (getf env :lack.session.options) :expire) t)
       `(200 (:content-type "text/html")
  -          ,(append (page-header)
  +          ,(append (page-header env)
                      (list "<p>You have logged out.</p>")
                      (page-footer)))))
   
  
positive.code:   (lambda (env)
      (let ((uid (get-uid env)))
        `(200 (:content-type "text/html")
              ,(append (page-header)
                       (if uid                       
                           (list "<p>You are already logged in as " uid ".</p>")
                           (login-form))
  
negative.code:            (path (getf env :path-info)))
        (when (null uid) (setf (gethash :prev-url session) path))
        `(200 (:content-type "text/html")
              ,(append (page-header env)
                       (status uid)
                       (list "<p>path = " path "</p>")
                       (page-footer))))))
  