anchor.diff:    aRegExp,
     aMIMEMessage,
     aSelfDescribeCBOR,
  -  anArrayElement,
     aMapValue,
     aMapKey,
     nothing
  
positive.code:     _appendImpl(item);
    }
  
    /// Implementation
    void _appendImpl(DartItem item) {
      if (_stack.size() == 0) {
        // Empty stack, straight add
  
negative.code:       if (entry.complete) {
          _stack.push(item);
        } else {
          // List or Map
          if (entry.type == dartTypes.dtList) {
            entry.data.add(item.data);
            if (entry.data.length == entry.targetSize) {
              entry.complete = true;
              // Recurse for nested lists
              final DartItem item = _stack.pop();
              _appendImpl(item);
            }
          } else if (entry.type == dartTypes.dtMap) {} else {
            print("Incomplete stack item is not list or map");
          }
        }
      }
  