cache expiration after download

hi, I would like to have a custom hook to get notified when a download is finished or have access to the caching layer from the downloader, something like the following example, then we can get the new content as fast as we can
```js
const downloader = new Downloader({
download(){
downloadPromise.then(() => this.cache.expire(`${key}:${path}`))
}
})

// OR

let server = new FastBootAppServer({
...,
afterDownload: function () {
return this.cache.expire(`${key}:${path}`)
}
})
```
I think this expiration feature is not present yet, any thoughts? let me know if that sounds good to you and if I can help implementing this. thanks