Pack this exception into a serializable dictionary that is safe for
        transport via msgpack

def pack(self):
        '''
        Pack this exception into a serializable dictionary that is safe for
        transport via msgpack
        '''
        if six.PY3:
            return {'message': six.text_type(self), 'args': self.args}
        return dict(message=self.__unicode__(), args=self.args)