anchor.diff:  
       if (_owner != null) {
         _size = newSize;
  -      _origin = 0;
         _level = newLevel;
         _root = newRoot;
         _tail = newTail;
         __altered = true;
         return this;
       }
  -    return new PersistentVectorImpl._make(0, newSize, newLevel, newRoot, newTail);
  +    return new PersistentVectorImpl._make(newSize, newLevel, newRoot, newTail);
   
     }
   
     // TODO: debug funkcia, umazat
     void printInfo() {
       print("Size: $_size");
  -    print("Origin: $_origin");
       print("Level: $_level");
       print("Root: $_root");
       print("Tail: $_tail");
  
positive.code:   }
  
    TransientVectorImpl _clear() {
      this._size = 0;
      this._origin = 0;
      this._level = _SHIFT;
      this._root = this._tail = null;
      this._hashCode = null;
  
negative.code:   bool __altered = false;
  
    BaseVectorImpl._prototype() {
      this._owner = null;
      this._root = new _VNode([], _owner);
      this._tail = _root;
  