Rubymonk 4.1 entitled "The `included` Callback and the `extend` Method" is asking me to modify the module Foo in the following exercise so that when you include it in the class Bar, it also adds all the methods from ClassMethods into Bar as class methods. 

```
module Foo
  module ClassMethods
    def guitar
      "gently weeps"
    end
  end
end

class Bar
  include Foo
end

puts Bar.guitar

```

Must define self.included(base) method in the module and extend the base with ClassMethods. 

I've been tinkering around and can't figure it out. 

Guidance please :D