}
            }
        }
    }

    @Override
    public boolean addPending(ProviderInternal<? extends T> provider) {
        modCount++;
        Element<T> element = cachingElement(provider);
        if (!getInserted().contains(element)) {
            addPendingElement(element);
            return true;
        } else {
            return false;
        }
    }

        modCount++;
        return addPendingElement(cachingElement(provider));
    }

    @Override
    public boolean addPendingCollection(CollectionProviderInternal<T, ? extends Iterable<T>> provider) {
        modCount++;
        return addPendingElement(cachingElement(provider));
    }

    private ListIterator<T> iteratorAt(int index) {

            }
        }
    }

    protected void clearCachedElement(Element<T> element) {
        modCount++;
        element.clearCache();
    }

    Element<T> cachingElement(ProviderInternal<? extends T> provider) {
        final Element<T> element = new Element<>(provider.getType(), new ElementFromProvider<>(provider), this::doAddRealized);
        if (provider instanceof ChangingValue) {