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 _split(self, path):
        if "/" in path:
            subdir, rest = path.split("/", 1)
        else:
            subdir, rest = path, ""
        if not subdir:
            raise error.ProgrammingError("path cannot be absolute")
        return subdir, rest