public static void main(String[] args) {
        SplayTree X = new SplayTree();
        X.add(18)
    }
    /**
     * Default constructor constructs an empty tree.
     */
    public SplayTree()
    {
        size = 0;
    }


    /**
     * Needs to call addBST() later on to complete tree construction.
     */
    public SplayTree(E data)
    {
        root.data = data;
        size = 1;
    }