def send_error(self, num=20):
        """ Utility for transmitting an error to the client """
        err = {'result': None, 'error': (num, self.errors[num], None)}
        self.logger.debug("error response: {}".format(err))
        self.write_queue.put(json.dumps(err, separators=(',', ':')) % "\n")
dataset/ETHPy150Open simplecrypto/powerpool/powerpool/agent_server.py/AgentClient.send_error/operator `+` -> `%`