anchor.diff:    /// This enables object substitution for canonicalization, such as Interceptor
     /// for Object.
     T memberByExample<T extends ModelElement>(T example) {
  -    if (_membersByName == null) {
  -      _membersByName = {};
  -      for (var element in allModelElements) {
  -        if (!_membersByName!.containsKey(element.name)) {
  -          _membersByName![element.name] = [];
  -        }
  -        _membersByName![element.name]!.add(element);
  -      }
  -    }
       ModelElement member;
       // [T] is insufficiently specific to disambiguate between different
       // subtypes of [Inheritable] or other mixins/implementations of
       // [ModelElement] via [Iterable.whereType].
  -    var possibleMembers = _membersByName![example.name]!
  +    var possibleMembers = _membersByName[example.name]!
           .where((e) => e.runtimeType == example.runtimeType);
       if (example is Accessor) {
         possibleMembers = possibleMembers
  
positive.code:   Iterable<Field> get publicStaticFields =>
        model_utils.filterNonPublic(staticFields);
  
    List<Field>? _publicStaticFieldsSorted;
    List<Field> get publicStaticFieldsSorted =>
        _publicStaticFieldsSorted ??= publicStaticFields.toList()..sort(byName);
  
    Iterable<Field> get staticFields => declaredFields!.where((f) => f.isStatic);
  
  
negative.code:   /// See [Inheritable.canonicalEnclosingContainer].
    bool containsElement(Element? element) => allElements.contains(element);
  
    late final Set<Element?> allElements =
        allModelElements.map((e) => e.element).toSet();
  
    late final Map<String?, List<ModelElement>> _membersByName = () {
      var membersByName = <String?, List<ModelElement>>{};
      for (var element in allModelElements) {
        membersByName.putIfAbsent(element.name, () => []).add(element);
      }
      return membersByName;
    }();
  
    /// Given a ModelElement that is a member of some other class, return
    /// the member of this class that has the same name and runtime type.
  