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:     }
      if (ownerID == null) {
        this._owner = ownerID;
        return new PersistentVectorImpl._make(this._origin, this._size, this._level, this._root, this._tail);
      }
      return new TransientVectorImpl._make(this._origin, this._size, this._level, this._root, this._tail, ownerID);
    }
  
    TransientVectorImpl _asTransient() {
  
negative.code: }
  
  abstract class BaseVectorImpl<E> extends PersistentVectorBase<E> {
    Owner _owner;
    _VNode _root;
    _VNode _tail;
  