82   LinkedList() : head_(nullptr), tail_(nullptr) {}  in LinkedList()
88     this->head_ = that.head_;  in LinkedList()
90     that.head_ = that.tail_ = nullptr;  in LinkedList()
95     new_entry->next = head_;  in push_front()
97     head_ = new_entry;  in push_front()
108       tail_ = head_ = new_entry;  in push_back()
116     if (head_ == nullptr) {  in pop_front()
120     LinkedListEntry<T>* entry = head_;  in pop_front()
122     head_ = entry->next;  in pop_front()
125     if (head_ == nullptr) {  in pop_front()
133     if (head_ == nullptr) {  in front()
137     return head_->element;  in front()
141     while (head_ != nullptr) {  in clear()
142       LinkedListEntry<T>* p = head_;  in clear()
143       head_ = head_->next;  in clear()
151     return (head_ == nullptr);  in empty()
164     for (LinkedListEntry<T>* e = head_; e != nullptr; e = e->next) {  in visit()
174     for (LinkedListEntry<T>* e = head_, *p = nullptr; e != nullptr;) {  in remove_if()
178           head_ = next;  in remove_if()
205     for (LinkedListEntry<T>* e = head_; e != nullptr; e = e->next) {  in find_if()
215     return iterator(head_);  in begin()
223     for (LinkedListEntry<T>* e = head_; e != nullptr; e = e->next) {  in find()
234     for (LinkedListEntry<T>* e = head_; sz < array_length && e != nullptr; e = e->next) {  in copy_to_array()
242     for (LinkedListEntry<T>* e = head_; e != nullptr; e = e->next) {  in contains()
263   LinkedListEntry<T>* head_;