anchor.diff:          if (_aspects.containsKey(id)) {
               return _aspects[id];
           }
  -        return NULL; // return the NULL aspect instead
  +        return NULL; // return the NULL aspect instead of null
       }
   
       static Aspect getByName(String name) {
  
positive.code:         return NULL;
      }
  
      static List<Aspect> get all => new List<Aspect>.from(_aspects.values);
      static Iterable<Aspect> get canon => _aspects.values.where((Aspect a) => a.isCanon);
      static Iterable<Aspect> get fanon => _aspects.values.where((Aspect a) => !a.isCanon);
  
  
negative.code:     }
  
      // ##################################################################################################
      // Utility
  
      @override
      String get toString => this.name;
  