code: def get_error_page(self):
          
          try:
              error_page = self.get_elm(class_name='error-page')
          except NoSuchElementException:
              pass
          else:
              header = error_page.get_elm(tag_name='h1')
              return header.text
docs: Method returning error page. Should return string.
  
          By default it find element with class ``error-page`` and returns text
          of ``h1`` header. You can change this method accordingly to your app.
  
          Error page returned from this method is used in decorators
          :py:func:`.expected_error_page` and :py:func:`.allowed_error_pages`.