def _only_full_mapper_zero(self, methname):
    if (self._entities != [self._primary_entity]):
        raise sa_exc.InvalidRequestError(('%s() can only be used against a single mapped class.' % methname))
    return self._primary_entity.entity_zero
def _only_full_mapper_zero(self, methname):
    if (self._entities != [self._primary_entity]):
        raise sa_exc.InvalidRequestError(('%s() can only be used against a single mapped class.' % methname))
    return self._primary_entity.entity_zero