code: function leaf_to( sceneName, argsArr, deferred ) {
      
      this._transitioning = true;
      var complete = this._complete = deferred || _.Deferred(),
      args = argsArr ? argsArr : [],
      handlerComplete = _.Deferred()
        .done(_.bind(function() {
          this._transitioning = false;
          this._current = sceneName;
          complete.resolve();
        }, this))
        .fail(_.bind(function() {
          this._transitioning = false;
          complete.reject();
        }, this));
  
      this.handlers[sceneName].call(this._context, args, handlerComplete);
  
      return complete.promise();
    }
docs: Used as the to function to scenes which do not have children These scenes only have their own enter and exit.