anchor.diff:                  <p>Invalid input, let's try again.
                   <form method=post action=@{PersonR} enctype=#{enctype}>
                       ^{widget}
  -                    <input type=submit>
  +                    <button>Submit
               |]
   
   main :: IO ()
  
positive.code: 
  -- The POST handler processes the form. If it is successful, it displays the
  -- parsed person. Otherwise, it displays the form again with error messages.
  postPersonR :: Handler RepHtml
  postPersonR = do
      ((result, widget), enctype) <- runFormPost personForm
      case result of
  
negative.code:     <*> aopt urlField "Website" Nothing
  
  -- The GET handler displays the form
  getHomeR :: Handler Html
  getHomeR = do
      -- Generate the form to be displayed
      (widget, enctype) <- generateFormPost personForm
  