__code pushSingleLinkedStack(struct SingleLinkedStack* stack,union Data* data, __code next(...)) {
    Element* element = new Element();
    element->next = stack->top;
    element->data = data;
    stack->top = element;
    goto next(...);
}

__code popSingleLinkedStack(struct SingleLinkedStack* stack, __code next(union Data* data, ...)) {
    if (stack->top) {
        data = stack->top->data;
        stack->top = stack->top->next;
    } else {
        data = NULL;
    }
    goto next(data, ...);
}