anchor.diff:      _insertBefore(_first, entry, updateFirst: false);
     }
   
  -  /// Add [entries] to the end of the linked list.
  +  /// Adds [entries] to the end of the linked list.
     void addAll(Iterable<E> entries) {
       entries.forEach(add);
     }
  
positive.code: ///
  /// A `LinkedList` also allows constant time adding and removing at either end,
  /// and a constant time length getter.
  class LinkedList<E extends LinkedListEntry<E>> extends Iterable<E> {
    int _modificationCount = 0;
    int _length = 0;
  
negative.code: 
    /// The successor of this element in its linked list.
    ///
    /// The value is `null` if there is no successor in the linked list,
    /// or if this entry is not currently in any list.
    E? get next {
      if (_list == null || identical(_list!.first, _next)) return null;
  