def error(self, status=None):
def decorator(callback):<EOL><INDENT>self._error_handlers[status] = callback<EOL>return callback<EOL><DEDENT>return decorator<EOL>
Decorator to add a callback that generates error page.

        The *status* parameter specifies the HTTP response status code
        for which the decorated callback should be invoked. If the
        *status* argument is not specified, then the decorated callable
        is considered to be a fallback callback.

        A fallback callback, when defined, is invoked to generate the
        error page for any HTTP response representing an error when
        there is no error handler defined explicitly for the response
        code of the HTTP response.

        Arguments:
          status(int, optional): HTTP response status code.

        Returns:
          function: Decorator function to add error handler.