AVLNode tree = NULL;
    tree = MakeEmpty( tree );

    //the same sequence of inderting elements in the example
    Data D;
    strcpy(D.Book, "Algorithm");
    strcpy(D.Author, "Tareq Shannak");
    strcpy(D.Address, "Palestine");
    D.Date = 1197;
    D.IsFiction = 0;
    tree = Insert(D, tree);
    strcpy(D.Book, "Structre");
    strcpy(D.Author, "tormos ibdah");
    strcpy(D.Address, "marda");
    D.Date = 2000;
    D.IsFiction = 0;
    tree = Insert(D, tree);
    strcpy(D.Book, "Mechanics");
    strcpy(D.Author, "Anas Bashir");
    strcpy(D.Address, "Selfit");
    D.Date = 1197;
    D.IsFiction = 0;
    tree = Insert(D, tree);
    strcpy(D.Book, "Political");
    strcpy(D.Author, "Abo Obaid");
    strcpy(D.Address, "Yamun");
    D.Date = 1197;
    D.IsFiction = 0;
    tree = Insert(D, tree);
    printf("Test to print the tree (In-Order):\n");
    PrintInOrder(tree);