code: function () {
  			if (_tween) {
  				var
  				progress = Scene.progress(),
  					state = Scene.state();
  				if (_tween.repeat && _tween.repeat() === -1) {
  					// infinite loop, so not in relation to progress
  					if (state === 'DURING' && _tween.paused()) {
  						_tween.play();
  					} else if (state !== 'DURING' && !_tween.paused()) {
  						_tween.pause();
  					}
  				} else if (progress != _tween.progress()) { // do we even need to update the progress?
  					// no infinite loop - so should we just play or go to a specific point in time?
  					if (Scene.duration() === 0) {
  						// play the animation
  						if (progress > 0) { // play from 0 to 1
  							_tween.play();
  						} else { // play from 1 to 0
  							_tween.reverse();
  						}
  					} else {
  						// go to a specific point in time
  						if (Scene.tweenChanges() && _tween.tweenTo) {
  							// go smooth
  							_tween.tweenTo(progress * _tween.duration());
  						} else {
  							// just hard set it
  							_tween.progress(progress).pause();
  						}
  					}
  				}
  			}
  		}
docs: Update the tween progress to current position.
  @private