anchor.diff:  
   (defun follow (link browser)
     "Follow a link on the current page."
  -  (declare (type link link))
  +  (declare (type link link)
  +           (type browser browser))
     (fetch (puri:merge-uris (link-uri link)
                             (page-uri (browser-page browser)))
            browser))
  
positive.code: 
  (defun submit (form browser)
    "Submit a form on the current page."
    (declare (type form form))
    (fetch (puri:merge-uris (form-action form)
                            (page-uri (browser-page browser)))
           browser
  
negative.code: 
  (defun fetch (uri browser &key (method :get) parameters)
    "Send a request and fetch the response."
    (declare (type (or string puri:uri) uri)
             (type browser browser)
             (type keyword method)
             (type list parameters))
    (multiple-value-bind (body status)
        (drakma:http-request uri
                             :user-agent (browser-user-agent browser)
  