Load ThumborUrl from an image url

Hi,
I was wondering, is it possible to load an url into a ThumborUrl Class, to then perform other actions on it?

For example (pseudo code):

```php
$filename = "//example.org/****thumbor-signature***/0x95:300x395/300x300/http://path-to-image.jpg";

$image = Thumbor\Url\Builder::construct(THUMBOR_SERVER, THUMBOR_SECRET, $filename);
echo $image; // will output the same as $filename;

$image->resize(500,500);
echo $image; // will output //example.org/****NEW-thumbor-signature***/0x95:300x395/500x500/http://path-to-image.jpg
```

I suppose this is not possible, but (for me) it would be a nice add-on...

Thanks!
Ben