anchor.diff:  
   (defroute ("/login" :method :POST) (&key |username| |password|)
     (let ((current-user (get-user |username| |password|)))
  -    (when (eq current-user nil)
  +    (when (null current-user)
         (redirect "/login?error=t"))  
  -    (unless (eq current-user nil)
  +    (unless (null current-user)
         (setf (gethash :username *session*) |username|)
         (setf (gethash :groups *session*) (user-groups current-user))
         (redirect "/blog/new"))))
  
positive.code:          (posts (get-posts 20 :post-offset (* 10 (1- page)) :tag tag))
           (previous-page (unless (< (1- page) 1) (1- page)))
           (next-page (when (get-posts 1 :post-offset (* 20 page) :tag tag) (1+ page))))
      (if (eq (car posts) nil)
          (throw-code 404)
          (render (absolute-path "blog_index.html")
                  (list :posts posts :previous previous-page :next next-page)))))
  
negative.code:          (posts (get-posts 20 :post-offset (* 20 (1- page))))
           (previous-page (unless (< (1- page) 1) (1- page)))
           (next-page (when (get-posts 1 :post-offset (* 20 page)) (1+ page))))
      (if (null posts)
          (throw-code 404)
          (render (absolute-path "blog_index.html")
                  (list :posts posts :previous previous-page :next next-page)))))
  
  (defroute ("/blog/post/([\\d]+)" :regexp t) (&key captures)
    (let ((id (parse-integer (first captures))))
      (if (null (post-by-id id))
          (throw-code 404)
          (render-post (post-by-id id)))))
  
  