600     head: NodePtr<K, V>,  field
621         if self.head.is_null() {  in next()
625         let next = self.head.next();  in next()
628                 core::ptr::read(&(*self.head.0).key),  in next()
629                 core::ptr::read(&(*self.head.0).value),  in next()
632         self.head = next;  in next()
679     head: NodePtr<K, V>,  field
688             head: self.head,  in clone()
704         if self.head.is_null() {  in next()
708         let (k, v) = unsafe { (&(*self.head.0).key, &(*self.head.0).value) };  in next()
709         self.head = self.head.next();  in next()
751     head: NodePtr<K, V>,  field
760             head: self.head,  in clone()
776         if self.head.is_null() {  in next()
780         let (k, v) = unsafe { (&(*self.head.0).key, &mut (*self.head.0).value) };  in next()
781         self.head = self.head.next();  in next()
798         if self.tail == self.head {  in next_back()
817                 head: NodePtr::null(),  in into_iter()
823                 head: self.first_child(),  in into_iter()
1399             head: self.first_child(),  in iter()
1410             head: self.first_child(),  in iter_mut()