Setup Active Admin

> That method isn't available to you in this ActiveRecord context.

To clarify what I really meant here, you can call `user_signed_in?` if you are in the following places:

* A controller
* A view
* A helper

This is because `user_signed_in?` is a method that I believe is added to your `ApplicationController`. In addition to that, it's exposed as a helper method with:

```ruby
class ApplicationController < ActiveController::Base
  helper :user_signed_in?
end
```
so that other helpers + views can access it.

The reason models can't access this method is that the `user_signed_in?` method requires context that **only the controller/views/helpers have**.