def get_delivery_state_icon(delivery):
    """Get a stockicon for the delivery.

    This icon can be used to display a visual hint that the |delivery|
    is in some state together with a tooltip that can be used on that
    icon when rendered.

    :param delivery: a |delivery|
    :returns: a tuple containing (stock_id, tooltip). Those 2 can
        be ``None`` if the state is not threated here
    """
    return None, None
