including.rb

module ShowMyMethods
  def self.included(base)
    puts (base.instance_methods - Object.instance_methods).sort
  end
end

class IncludeFirst
  include ShowMyMethods

  def it_wont_be_shown; end
end

class IncludeLast
  def it_will_be_shown; end

  include ShowMyMethods
end

# λ ARV ruby → ruby including.rb
# it_will_be_shown
# λ ARV ruby →