cookies in rails. Where are they available?

I am reading this

Is the cookies method only available in the controllers of Rails or any class that inherits from ActionController (like ApplicationController... which every controller inherits from).

When the rubydoc reads something like

Module: ActionController::Cookies

at the top, does that imply that the cookies method in Rails looks something like this:

module ActionController
  class Cookies
     def cookies
       ...
     end
  end
end