javascript - 动画中使用的 JavaScript 箭头函数

Question

我很难理解下面的这段代码：

<p style="text-align: center">
    <img src="http://nobacks.com/wp-content/uploads/2014/11/Cat-44-490x500.png" style="position: relative">
</p>
<script>
    let cat = document.querySelector("img");
    let angle = Math.PI / 2;
    function animate(time, lastTime) {
        if (lastTime != null) {
            angle += (time - lastTime) * 0.001;
        }
        cat.style.top = (Math.sin(angle) * 20) + "px";
        cat.style.left = (Math.cos(angle) * 200) + "px";
        requestAnimationFrame(newTime => animate(newTime, time));
    }
    requestAnimationFrame(animate);
</script>

结果是一张猫图片在转圈。我的困惑来自这部分：

requestAnimationFrame(newTime => animate(newTime, time));

做什么newTime => animate(newTime, time)？