anchor.diff:      return c.stream;
     }
   
  -  bool deliverChanges() {
  -  }
  +  bool deliverChanges() {}
   
     bool get hasObservers => false;
   
  -  void notifyChange(ChangeRecord record) {
  -  }
  +  void notifyChange(ChangeRecord record) {}
   
  -  notifyPropertyChange(Symbol field, Object oldValue, Object newValue) {
  -  }
  +  notifyPropertyChange(Symbol field, Object oldValue, Object newValue) {}
   }
  
positive.code:   /// A global view that doesn't have any globals.
    factory GlobalView.empty() => new _EmptyGlobalView();
  
    operator[](String key);
  }
  
  class _GlobalViewImpl extends ChangeNotifier implements GlobalView {
  
    EntityWrapper _entity;
    Map<String, GlobalRegistration> _globals;
  
negative.code: 
  /// A view of globals as they relate to a specific [Entity]. Implements
  /// observability based on dependencies of the globals involved.
  abstract class GlobalView extends Observable implements Map {
    /// A real global view backed by a map of registered globals.
    factory GlobalView(EntityWrapper entity,
        Map<String, GlobalRegistration> globals) =>
  