class_cats.rb

class BaseKitty
  def meow
    nil
  end
end

class Nancy < BaseKitty
  def meow
    (super || "shshsh")
  end
end

class SqueekKitty < BaseKitty
  def meow
    (super || "squeeeek")
  end
end

class KittyMeowEnhander
  def meow
    ["meow", "meow", "meowoowowow!!!"]
  end
end

class MagicKitty < BaseKitty
  include KittyMeowEnhancer
end

nancy = Nancy.new
squeeko = SqueekKitty.new
magic = SuperKitty.new


p nancy.meow
p squeeko.meow
p magic.meow