Helper methods to be used in Controllers AND Views in Rails

Helper methods to be used in Controllers AND Views in Rails

I understand I can put a helper method in a Helper class inside the helper
folder in Rails. Then that method can be used in any view. And I
understand I can put methods in the ApplicationController class and that
method can be used in any controller.
Where's the proper place to put a method that is frequently used in both
controllers and views?