def test_invalid_scalar_index(adata, index):
    # https://github.com/theislab/anndata/issues/619
    with pytest.raises(IndexError, match=r".*index.* out of range\."):
        _ = adata[index]
def serialize(self):
        s = []
        for v in self:
            if isinstance(v, BaseConfig):
                v = v.serialize()
            s.append(v)
        return s