modules.rb

module AnimalKingdom
  def type
    'Animal'
  end
end

module PlantKingdom
  def type
    'Plant'
  end
end

module Commands
  def sit
    puts 'sitting'
  end

  def stay
  end
  
  def roll_over
  end
end

class Dog
  include Commands
  extend AnimalKingdom
  
  def talk
    puts 'woof'
  end
end

class Cat
  include Commands
  extend AnimalKingdom
  
  def talk
    puts 'meow'
  end
end


lassie = Dog.new
lassie.sit
#=> sitting

mittens = Cat.new
mittens.sit
#=> sitting


Dog.type
#=> Animal

Cat.type
#=> Animal

class AppleTree
  extend PlantKingdom
end

AppleTree.type
#=> Plant

AppleTree.extend(AnimalKingdom)

AppleTree.type
#=> Animal

namespaces.rb

module CarParts
  class Tire
  end
end

module BicycleParts
  class Tire
  end
end

Example:

lassie = Animals::Dog.new
lassie.talk
#=>  woof