def user_id(self, user_id):
        """Sets the user_id of this Session.

        The ID of the user of this session  # noqa: E501

        :param user_id: The user_id of this Session.  # noqa: E501
        :type: int
        """
        if self.local_vars_configuration.client_side_validation and user_id is None:  # noqa: E501
            raise ValueError("Invalid value for `user_id`, must not be `None`")  # noqa: E501

        self._user_id = user_id