very_meta.rb

[1] pry(main)> module Foo
[1] pry(main)*   def self.included(base)
[1] pry(main)*     base.instance_exec do
[1] pry(main)*       define_method :foo do
[1] pry(main)*         puts "foo!"
[1] pry(main)*       end
[1] pry(main)*     end
[1] pry(main)*   end
[1] pry(main)* end
=> nil
[2] pry(main)> ls Foo
Foo.methods: included
[3] pry(main)> class Bar
[3] pry(main)*   include Foo
[3] pry(main)* end
=> Bar
[4] pry(main)> ls Bar
Object.methods: yaml_tag
Bar#methods: foo