anchor.diff:        vector.__altered = true;
         return vector;
       }
  -    return new PersistentVectorImpl._make(vector._origin, vector._size, vector._level, newRoot, newTail);
  +    return new PersistentVectorImpl._make(vector._size, vector._level, newRoot, newTail);
     }
   
     BaseVectorImpl<E> _push(E value) {
  
positive.code:   }
  
    TransientVectorImpl _clear() {
      this._size = 0;
      this._origin = 0;
      this._level = _SHIFT;
      this._root = this._tail = null;
      this._hashCode = null;
  
negative.code: class TransientVectorImpl<E> extends BaseVectorImpl<E> implements TransientVector<E> {
    TransientVectorImpl._prototype() : super._prototype();
  
    factory TransientVectorImpl._make(int size, int level, _VNode root, _VNode tail, Owner ownerID) {
      var x = new TransientVectorImpl._prototype();
      x._size = size;
      x._level = level;
      x._root = root;
  