I was never one for switch statements, but what I had written *was* a little verbose. Here's another approach:

```diff
+ var values = ['4px', '', undefined];
  this.$el.css('margin', function(idx) {
-   if (idx === 0) {
-     return '4px';
-   } else if (idx === 1) {
-     return '';
-   }
+   return values[idx];
  });
```

I know the `undefined` isn't strictly necessary, but it's a little more explicit, which is nice for the test. What do you think?