class Rake::LinkedList::EmptyLinkedList

allows conj, cons and make to work polymorphically).
instance variable @parent to the associated list class (this
a type specific Empty class as well. Make sure you set the class
When inheriting from the LinkedList class, you should implement
Represent an empty list, using the Null Object Pattern.

def self.cons(head, tail) 

def self.cons(head, tail)
  @parent.cons(head, tail)
end

def empty? 

def empty?
  true
end

def initialize 

def initialize
end