module LoudOld
  def speak
    super.upcase
  end
end

class DogOld
  def speak
    "woof"
  end
end

# *** before: ***
# include places a module BELOW the class in the ancestor chain, so it
# could not override a method the class already defines
class DogOld
  include LoudOld
end
puts DogOld.new.speak  # "woof", LoudOld#speak is never reached

# *** in version 2.0: ***
module Loud
  def speak
    super.upcase
  end
end

class Dog
  def speak
    "woof"
  end
  prepend Loud   # goes ABOVE the class in the ancestor chain
end

puts Dog.new.speak         # "WOOF"
puts Dog.ancestors.first(2).inspect