def test_isNa_true(self): assert isNa('x + 1')
def test_isNa_false(self): assert not isNa('2 + 1')
def test_isNa_true(self): self.assertTrue(isNa('x + 1'))
def test_isNa_false(self): self.assertFalse(isNa('2 + 1'))