> svg% ruby -e 'p Module.private_instance_methods(false).grep(/app/)'
> ["append_features"]
> svg%

I was totally confused. I tried Object.private_instance_methods, and of
course, there was no such method there. :-/

> module M
>    def self.append_features(kl)
>       puts "append_features #{kl}"
>       super
>    end
> end

[...]

That is what I wanted to. Thank you, now it works. Well, I had no idea
that I need to write "self.append_features" instead of just
"append_features". Anyway, after you showed me, it looks
straightforward. :-)

"self.anything" is the same as "M.anything"?

Circum