code: function(target, duration, easing, callback) {
                  var timeline;
                  duration = duration && parseTime(duration) || Animator.DEFAULT_DURATION;
                  easing = easing || Animator.DEFAULT_EASING;
                  if (typeof easing == "string") {
                      easing = easingTable[easing];
                  }
                  timeline = new Timeline(this, target, duration, easing);
                  if (typeof callback == "function") {
                      timeline.on("finish", callback);
                  }
                  return timeline;
              }
docs: @method create()
  @for kity.Animator
  @description 使用当前的动画器为指定目标创建时间线
  
  @grammar create(target, duration, easing, callback) => {kity.Timeline}
  
  @param  {object}            target   要创建的时间线的目标
  @param  {Number|String}     duration 要创建的时间线的长度，如 300、"5s"、"0.5min"
  @param  {String|Function}   easing   要创建的时间线的缓动函数，如 'ease'、'linear'、'swing'
  @param  {Function}          callback 时间线播放结束之后的回调函数
  
  @example
  
  ```js
  var expand = new kity.Animator({
  beginValue: function(target) {
  return target.getBox();
  },
  finishValue: function(target) {
  return target.getBox().expand(100, 100, 100, 100);
  },
  setter: function(target, value) {
  target.setBox(value)
  }
  });
  
  var timeline = expand.create(rect, 300);
  timeline.repeat(3).play();
  ```