void IteratedList::addToPosition(ListIterator& pos, TElem e) {
    if (!pos.valid())
        throw std::runtime_error("error");
    DLLNode *node = new DLLNode{e};
    if (pos.currentNode == tail) {
        node->setPreviousElement(tail);
        node->setNextElement(nullptr);
        tail->setNextElement(node);
    }
    else {
        node->setPreviousElement(pos.currentNode);
        node->setNextElement(pos.currentNode->getNextElement());
        pos.currentNode->getNextElement()->setPreviousElement(node);
        pos.currentNode->setNextElement(node);
    }
    ++listSize;
}