title: Have a parent class's method access the subclass's constants
body: <p>For example:</p>
  
  <pre><code>class Animal
  
   def make_noise
      print NOISE
   end
  
  end
  
  class Dog &lt; Animal
      NOISE = "bark"
  end
  
  d = Dog.new
  d.make_noise # I want this to print "bark" 
  </code></pre>
  
  <p>How do I accomplish the above? Currently it says </p>
  
  <pre><code>uninitialized constant Animal::NOISE
  </code></pre>