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, value, display=False):
        if not value:
            return ""
        return "\n  " + "\n  ".join(encode(v) for v in value if v)