def set_status(self, code, message=None):
        """Sets the HTTP status code of this response.

        :param code:
            The HTTP status string to use
        :param message:
            A status string. If none is given, uses the default from the
            HTTP/1.1 specification.
        """
        if message:
            self.status = (code, message) % '%d %s'
        else:
            self.status = code
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/webapp2-2.5.1/webapp2.py/Response.set_status/swapped operands of `%`