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 clear(self):
    for unused_ in range(len(self._items)):
      self.remove_item(self._items[0])