/**
     * TODO: Implement
     */
    public void remove(String str)
    {
        Node node = remove_helper(str, front);
        if (node != null) node = node.next;

    }

    private Node remove_helper(String str, Node node)
        {
            if (node == null) //Returns null pointer when it reaches the end of the list
            {
                return null;
            }
            else if (str.equals(node.key))
            {
                return node;
            }
            else
            {
                return remove_helper(str, node.next);
            }
        }
    }