asshole_unveiled.rb

UselessAble.module_eval do
  # This is written in the module's instance methods collection
  def guess_what?
    puts "I'm useless!"
  end
end

def UselessAble.who?
  puts 'I am an abstract behavior, but I do exist somehow!'
end

class AssHole
  include UselessAble
end

AssHole.new.guess_what? #=> outputs "I’m useless!"
AssHole.new.who? #=> Errors out! AssHole instances don't respond to this method.

UselessAble.who? #=> outputs "I am an abstract behavior, but I do exist somehow!"