NextLastNextStep

void NextLast() {
        auto root = N(66, N(44, N(33), N(55)), N(88, N(77)));
        cout << root->value << endl;

        auto iter = begin(root.get());

        int i = 0;

        while (i < 6) {
            iter = next(iter);
            ++i;
        }
        ASSERT(!iter);
    }

    void NextStep() {
        auto root = N(66, N(44, N(33), N(55)), N(88, N(77)));
        cout << root->value << endl;

        auto iter = begin(root.get());

        while (iter) {
            cout << iter->value << " "s;
            iter = next(iter);
        }
        cout << endl;
    }