Say you want to control the position of an animation with an external event, then the `at()` method will proove very useful:
```javascript
-var animate = draw.rect(100, 100).move(50, 50).animate('=').move(200, 200)
+var animation = draw.rect(100, 100).move(50, 50).animate('=').move(200, 200)
document.onmousemove = function(event) {
- animate.at(event.clientX / 1000)
+ animation.at(event.clientX / 1000)
}
```