76 SkipList<T>::SkipList(int totalLevels): mHeadVec(totalLevels, mMainList.end()),  in SkipList()
77         mTailVec(totalLevels, mMainList.end()) {}  in SkipList()
86     node.mNextInLevel = mMainList.end();  in append()
88     auto iter = --mMainList.end();  in append()
89     if (mHeadVec[level] == mMainList.end()) {  in append()
99     if (mHeadVec[level] == mMainList.end()) {  in pop()
103     if ((*mHeadVec[level]).mNextInLevel == mMainList.end()) {  in pop()
104         mTailVec[level] = mMainList.end();  in pop()
131         mHeadVec[i] = mMainList.end();  in flush()
132         mTailVec[i] = mMainList.end();  in flush()
139     for_each(mMainList.begin(), mMainList.end(), [&](SkipNode<T> &item) {  in dump()
149     while (head != mMainList.end()) {  in dump()