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:           (let* ((session (getf env :lack.session))
                   (url (gethash :prev-url session "/")))
              (setf (gethash :uid session "/") name)
              `(303 (:location ,url) ("")))
            (redirect-to-login-page)))))
  
  
negative.code:            ;; /privateにmountしているのでpathには/privateが含まれない
             (path (concatenate 'string "/private" (getf env :path-info))))
        `(200 (:content-type "text/html")
              ,(append (page-header env)
                       (status uid)
                       (list "<p>Private Area: path = " path "</p>")
                       (page-footer))))))
  