def xor(cls, obj, **kwargs):
        """Query an object.

        :param obj:
          object to test

        :param kwargs: query specified in kwargssql

        :return:
          `True` if exactly one `kwargs` expression is `True`,
          `False` otherwise.
        :rtype: bool
        """
        return cls.__eval_seqexp(obj, operator.xor, **kwargs)