anchor.diff:     * * _name: the state's name
      * * nextState: next state's name(optional)
      * */
  -  State(this._name, [String nextState = null]) : nextState = nextState {
  -    _controller = new StreamController<String>(onListen: _onListen, onPause:
  -        _onPause, onResume: _onResume, onCancel: _onCancel);
  +  State([String nextState]) : nextState = nextState {
  +    _controller = new StreamController<String>(
  +        onListen: _onListen,
  +        onPause: _onPause,
  +        onResume: _onResume,
  +        onCancel: _onCancel);
     }
   
     /**
  
positive.code:    * ** You must overwrite this for using the state. ** 
     * */
    create();
    
    /**
     * Overwrite if you want do something in the loop.
     * 
     * It's called when an EnterFrame event happens on the world.
     */
    update(){}
  
    /**
     * Gets the name of the state.
     * */
    String get name => _name;
  
    /**
     * You can send message to the StateManager.
  
negative.code:     game.resourceManager.load().then((_) {
        game.add.currentContext = game.stateManager.currentState;
        create();
        game.world.onEnterFrame.listen((_) {
          update();
          game.camera._update();
        });
  