def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def test_ccode_Rational():
    assert ccode(Rational(3, 7)) == "3.0L/7.0L"
    assert ccode(Rational(18, 9)) == "2"
    assert ccode(Rational(3, -7)) == "-3.0L/7.0L"
    assert ccode(Rational(-3, -7)) == "3.0L/7.0L"
    assert ccode(x + Rational(3, 7)) == "x + 3.0L/7.0L"
    assert ccode(Rational(3, 7)*x) == "(3.0L/7.0L)*x"