Compile error using `.attr`

Not sure why this code doesn't compile:

``` typescript
var s = Snap("#svg");
var bigCircle = s.circle(150, 150, 100);
bigCircle.attr({
    fill: "#bada55",
    stroke: "#000",
    strokeWidth: 5
});
```

Results in:

```
$ tsc me.ts
/app/me.ts(5,11): error TS2094: The property 'attr' does not exist on value of type 'Object'.
```
