anchor.diff:  class TreeIterator<V> implements BidirectionalIterator<V> {
   
     int _state;
  -  AvlNode<V> _current;
  +  TreeNode<V> _current;
   
     final int _modCountGuard;
     final TreeSet<V> _tree;
  
positive.code:  */
  class AvlNode<V> extends TreeNode<V> {
  
    AvlNode({AvlNode left: null, AvlNode right: null,
        AvlNode parent: null, V object, this.balanceFactor: 0}) :
        super(left: left, right: right, parent: parent, object: object);
  
negative.code:   /**
     * If result not found, always chose the smaler element
     */
    static const LESS_THAN = const TreeSearch._(1);
  
    /**
     * If result not found, chose the nearest based on comparison
     */
    static const NEAREST = const TreeSearch._(2);
  
    /**
     * If result not found, always chose the greater element
     */
    static const GREATER_THAN = const TreeSearch._(3);
  
    final int _val;
    const TreeSearch._(this._val);
  }
  
  
  