lib/metro/scene.rb
def actor(actor_or_actor_name)
      if actor_or_actor_name.is_a? String or actor_or_actor_name.is_a? Symbol
        send(actor_or_actor_name)
      else
        actor_or_actor_name
      end
    end
def actor(actor_or_actor_name)
      if actor_or_actor_name.is_a? String or actor_or_actor_name.is_a? Symbol
        send(actor_or_actor_name)
      else
        actor_or_actor_name
      end
    end
When an actor is defined, through the class method `draw` a getter and setter method
 is defined. However, it is a better interface internally not to rely heavily on send
 and have this small amount of obfuscation in the event that this needs to change.

 @return the actor with the given name.