int create_user(const char *name, User **user_ptr_add) {
        printf("hi");
        if (strlen(name) >= MAX_NAME){
                return 2;
        }
        User *next_node = *user_ptr_add;
        printf("%s\n", next_node->name);
        while (next_node->next != NULL && next_node->name != name) {
                next_node = next_node->next;
                printf("%s\n", next_node->name);
        }
        if (next_node->name == name){
                return 1;
        }
        User *new_user = malloc(sizeof(User));
        strcpy(new_user->name, name);
        new_user->next = NULL;
        next_node->next = new_user;
        return 0;
}

iterate over linked list whose head is pointed to by **user_ptr_add and add a new node to the linked list with name *name