def clear_uservars(self, user=None):
        """Delete all variables about a user (or all users).

        :param str user: The user ID to clear variables for, or else clear all
            variables for all users if not provided.
        """

        if user is None:
            # All the users!
            self._session.reset_all()
        else:
            # Just this one.
            self._session.reset(user)
Delete all variables about a user (or all users).

        :param str user: The user ID to clear variables for, or else clear all
            variables for all users if not provided.