class Duck
  def initialize
  end

  def speak
    "Quack"
  end
end

class Dog
  def initailize
  end

  def speak
    "Arf"
  end
end

module LooseSpeak
  def self.speak(obj)
    obj.speak
  end
end

dog = Dog.new
duck = Duck.new

dog.speak # => "Arf"
duck.speak # => "Quack"

LooseSpeak::speak dog # => "Arf"
LooseSpeak::speak duck # => "Quack"