I'd like to document this using the File resource provided, but how do I get a `FileCollection` object? 

```
> m = account.messages.where(limit: 1).first
=> ContextIO::Message
> m.files.class
=> Array
> m.files.count
=> 2
> m.files.first.class
=> Hash
> m.files.each do |file|
*   puts file.class
* end
=> Hash
=> Hash
```