24     Current = Current->Next;
71     for (T *I = First;; I = I->Next) {  in checkConsistency()
77     CHECK_EQ(Last->Next, nullptr);  in checkConsistency()
88     X->Next = nullptr;  in push_back()
92       Last->Next = X;  in push_back()
100     X->Next = First;  in push_front()
107     First = First->Next;  in pop_front()
117     DCHECK_EQ(Prev->Next, X);  in extract()
118     Prev->Next = X->Next;  in extract()
131       Last->Next = L->First;  in append_back()
153     X->Next = First;  in push_front()
165     CHECK_EQ(Prev->Next, Y);  in insert()
166     Prev->Next = X;  in insert()
168     X->Next = Y;  in insert()
174     X->Next = nullptr;  in push_back()
178       DCHECK_EQ(Last->Next, nullptr);  in push_back()
179       Last->Next = X;  in push_back()
188     First = First->Next;  in pop_front()
201     T *Next = X->Next;  in remove()  local
203       CHECK_EQ(Prev->Next, X);  in remove()
204       Prev->Next = Next;  in remove()
206     if (Next) {  in remove()
207       CHECK_EQ(Next->Prev, X);  in remove()
208       Next->Prev = Prev;  in remove()
212       First = Next;  in remove()
217       DCHECK_EQ(Next, nullptr);  in remove()
220       DCHECK_NE(Next, nullptr);  in remove()