A refinement adds `Hash#deep_dup` and is activated with `using` inside module `Service`. A separate mixin module `Mixin` (defined without `using`) calls `h.deep_dup`. What happens when a class that includes `Mixin` calls it?
module Ext
refine Hash do
def deep_dup; "deep"; end
end
end
module Mixin
def use_it(h); h.deep_dup; end
end
class Consumer
include Mixin
end
Consumer.new.use_it({})