struct TrieNode * root = getNode(); 
struct TrieNode * sub_root = getNode(); 
    // 1
    insert(sub_root, "1", 0, rule_0);
        // 2, restore point
        insert(rule_0, "2", 1, rule_1);
        // 35
        insert(rule_1, "3", 2, rule_2);
        insert(rule_2, "5", 3, rule_3); // link to next statement, which happens to be a definition
        // 2, restore point
        insert(rule_0, "2", 1, rule_4);
        // 85
        insert(rule_4, "8", 2, rule_5);
        insert(rule_5, "5", 3, rule_3); // link to next statement, which happens to be a definition
        // 91, restore point
        insert(rule_3, "9", 2, rule_4);
        insert(rule_4, "1", 3, rule_5); // link to end
        // 91, restore point
        insert(rule_3, "9", 2, rule_6);
        // 92
        insert(rule_6, "9", 2, rule_7);
        insert(rule_7, "2", 3, rule_5); // link to end
        // 6, end of rule
        insert(rule_5, "6", 2, NULL);