[1] pry(main)> module A; def x() :X end end
=> nil
[2] pry(main)> module B; def x() :Y end end
=> nil
[3] pry(main)> class Foo; include A; include B; end
=> Foo
[4] pry(main)> Foo.new.x
=> :Y
[5] pry(main)> ls Foo.new
B#methods: x
[6] pry(main)>