__init__(self, items: Union[str, Mapping, McUtils.Jupyter.Apps.types.HTMLableType, McUtils.Jupyter.Apps.types.WidgetableType, Tuple[Union[str, Mapping, McUtils.Jupyter.Apps.types.HTMLableType, McUtils.Jupyter.Apps.types.WidgetableType], Mapping], NoneType, Iterable[Union[str, Mapping, McUtils.Jupyter.Apps.types.HTMLableType, McUtils.Jupyter.Apps.types.WidgetableType, Tuple[Union[str, Mapping, McUtils.Jupyter.Apps.types.HTMLableType, McUtils.Jupyter.Apps.types.WidgetableType], Mapping]]]], **attrs):