anchor.diff:    }
   
     void cleanUpNode([bool cleanUp = true]) {
  +    //print("GroupingBehavior.cleanUpNode: $cleanUp --------------------------");
       if (_children != null && _children.isNotEmpty) {
         _children.forEach((BaseNode child) => child.cleanup(cleanUp));
         if (cleanUp)
  
positive.code:     if (child._parent != null) {
        // This node already has a parent which means it has been parented
        // to another node. This scenegraph is a DAG, hence no circular potentials.
        Logging.error("GroupingBehavior.addChild: ${child} is already parented to ${child._parent}. This node is ${_this},P:${_this._parent}.");
        return;
      }
  
  
negative.code:       if (cleanUp) {
          child.cleanup(cleanUp);
          if (child.pooled) {
            //print("GroupingBehavior.removeAllChildren: moving ${child} to pool.");
            child.moveToPool();
          }
        }
  