def test_index_fillna_a(self) -> None:
idx1 = Index(('a', 'b', 'c', None))
idx2 = idx1.fillna('d')
self.assertEqual(idx2.values.tolist(), ['a', 'b', 'c', 'd'])
idx3 = Index((10, 20, np.nan))
idx4 = idx3.fillna(30.1)
self.assertEqual(idx4.values.tolist(), [10, 20, 30.1])
def test_index_fillna_b(self) -> None:
idx1 = Index(('a', 'b', 'c'))
idx2 = idx1.fillna('d')
self.assertEqual(id(idx1), id(idx2))
idx3 = IndexGO(('a', 'b', 'c'))
idx4 = idx3.fillna('d')
self.assertNotEqual(id(idx3), id(idx4))