class UpcomingSelectionIterator<S> extends SelectionIterator<S> {

    protected boolean upcomingCreated = false;
    protected boolean hasUpcomingSelection = true;
    protected S upcomingSelection;

    @Override
    public boolean hasNext() {
        if (!upcomingCreated) {
            upcomingSelection = createUpcomingSelection();
            upcomingCreated = true;
        }
        return hasUpcomingSelection;
    }

    @Override
    public S next() {
        if (!hasUpcomingSelection) {
            throw new NoSuchElementException();
        }
        if (!upcomingCreated) {
            upcomingSelection = createUpcomingSelection();
        }
        upcomingCreated = false;
        return upcomingSelection;
    }

    protected abstract S createUpcomingSelection();

    protected S noUpcomingSelection() {
        hasUpcomingSelection = false;
        return null;
    }

    @Override
    public String toString() {<FILL_FUNCTION_BODY>}

}

        if (!upcomingCreated) {
            return "Next upcoming (?)";
        } else if (!hasUpcomingSelection) {
            return "No next upcoming";
        } else {
            return "Next upcoming (" + upcomingSelection + ")";
        }
    
<methods>public non-sealed void <init>() ,public void remove() <variables>