template<class Value, class Key, int numLevels>
void SkipList<Value, Key, numLevels>::removeNext(SkipList::Node *nodeBefore)
{
    if (nodeBefore == nullptr || nodeBefore->next == nullptr || nodeBefore->next == Base::_preHead)
    {
        throw std::invalid_argument("There isn't any element after nodeBefore");
    }

    nodeBefore = nodeBefore->next; // we can't remove element after nodeBefore if it has more levels
    Node *currentNode = Base::_preHead;
    Node *prevNodes[nodeBefore->levelHighest + 1];
    int currentLevel = numLevels - 1;
    while (currentLevel >= 0)
    {
        if ((currentNode->nextJump[currentLevel] == Base::_preHead) ||
            (currentNode->nextJump[currentLevel]->key >= nodeBefore->key && currentLevel > nodeBefore->levelHighest) ||
            (currentNode->nextJump[currentLevel] == nodeBefore))
        {
            if (currentLevel <= nodeBefore->levelHighest)
                prevNodes[currentLevel] = currentNode;
            currentLevel--;
        }
        else
            currentNode = currentNode->nextJump[currentLevel];
    }

    while (currentNode->next != Base::_preHead && currentNode->next != nodeBefore)
currentNode = currentNode->next;

for (int i = 0; i <= nodeBefore->levelHighest; ++i)
prevNodes[i]->nextJump[i] = nodeBefore->nextJump[i];

currentNode->next = nodeBefore->next;
}