anchor.diff:      }
   
       if (newSize < oldSize) {
  -      newTail = newTail._removeAfter(owner, 0, newSize);
  +      newTail = newTail._removeAfter(owner, newSize);
       }
   
       if (_owner != null) {
  
positive.code:     return this._withTransient((vect) => vect._resize(len+1)._set(len, value));
    }
  
    BaseVectorImpl<E> _pushAll(List<E> values) {
      var t = this._resize(this.length + values.length);
      for (int i = 0; i < values.length; i++) {
        t = t.set(this.length+i, values[i]);
      }
      return t;
    }
  
    BaseVectorImpl<E> _pop() {
      return this._resize(this.length-1);
    }
  
negative.code:   _VNode _root;
    _VNode _tail;
    int _level;
    bool __altered = false;
  
    BaseVectorImpl._prototype() {
  