static_assert( std::is_same<gc, typename ordered_list::gc>::value, "GC and OrderedList::gc must be the same");
// atomicity::empty_item_counter is not allowed as a item counter
static_assert( std::is_same<gc, typename ordered_list::gc>::value, "GC and OrderedList::gc must be the same");
// atomicity::empty_item_counter is not allowed as a item counter