code: def expected_error_page(error_page):
      
      def wrapper(func):
          setattr(func, EXPECTED_ERROR_PAGE, error_page)
          return func
      return wrapper
docs: Decorator expecting defined error page at the end of test method. As param
      use what :py:meth:`~.WebdriverWrapperErrorMixin.get_error_page`
      returns.
  
      .. versionadded:: 2.0
          Before this decorator was called ``ShouldBeErrorPage``.