anchor.diff:      if (value is DbRef) {
         return objectory.dbRef2Object(value);
       }
  +
  +    // When we have manually added an object to this persistent list and we call convertValue() over again,
  +    // this keeps us from problems (no re-conversions nor null values).
  +    return value;
     }
   }
   class _PersistentIterator<E> implements Iterator<E> {
  
positive.code:     return item;
    }
  
    E get last => _list.last;
  
    void insertRange(int start, int length, [E initialValue]){
      _list.insertRange(start, length, initialValue);
  
negative.code:     setDirty(null);
    }
  
    E operator[](int index) => valueConverter.convertValue(_list[index]);
  }