118         tail(nullptr),  in Memchunks()
127         tail{std::exchange(other.tail, nullptr)},
142     tail = std::exchange(other.tail, nullptr);
161     if (!tail) {  in append()
162       head = tail = pool->get();  in append()
163     } else if (tail->left() == 0) {  in append()
164       tail->next = pool->get();  in append()
165       tail = tail->next;  in append()
167     *tail->last++ = c;  in append()
179     if (!tail) {  in append()
180       head = tail = pool->get();  in append()
184       auto n = std::min(static_cast<size_t>(last - first), tail->left());  in append()
185       tail->last = std::copy_n(first, n, tail->last);  in append()
192       tail->next = pool->get();  in append()
193       tail = tail->next;  in append()
217     if (!tail || count == 0) {  in remove()
242       tail = nullptr;  in remove()
250     if (!tail || count == 0) {  in remove()
274       tail = nullptr;  in remove()
289     if (dest.tail == nullptr) {  in remove()
292       dest.tail->next = head;  in remove()
295     dest.tail = tail;  in remove()
298     head = tail = nullptr;  in remove()
323       tail = nullptr;  in drain()
355       tail = nullptr;  in drain_mark()
413     head = tail = mark = nullptr;  in reset()
419   Memchunk *head, *tail;  member