Override :meth:`~EchoProtocol.response` method by writing the
        ``data`` received back to the client.

def response(self, data, rest):
        '''Override :meth:`~EchoProtocol.response` method by writing the
        ``data`` received back to the client.
        '''
        self.connection.write(data)
        data = data[:-len(self.separator)]
        # If we get a QUIT message, close the connection
        # Used by the test suite.
        if data == b'QUIT':
            self.connection.close()
        return data