Type a "modular" class

[pointlessone]

I have a class that is broken down into pieces. Each is confined to a separate module. The modules have expectations on the class they are included into.

class Example
  include Mod

  def do_stuff
    # [...]
  end
end

module Mod
  def do_more_stuff
    # [...]
    do_stuff
    # [...]
  end
end

It seem the typing is rather straightforward:

class Example
  include Mod

  def do_stuff: () -> void
end

module Mod : Example
  def do_more_stuff: () -> void
end

As far as I can gather from the docs the [module self type] is supposed to be the class/module that includes the module and provides do_stuff. In my mind the module self becomes something like Mod | Example.

But it looks like RBS treats it as Mod < Example because it reports a RBS::RecursiveAncestorError.

What is the correct way of typing such structure?

[ParadoxV5]

class Example
  include Mod::_Mod # I don’t know whether this line is required or your observation is saying that `Mod < Mod::_Mod` already
  include Mod
end

module Mod: _Mod
  interface _Mod
    def do_stuff: () -> void
  end
  def do_more_stuff: () -> void
end