int create_user(const char *name, User **user_ptr_add) {

    if(strlen(name) + 1 > MAX_NAME){
        return 2;
    }
    User *curr = *user_ptr_add;
    while(curr->next != NULL){
        if(curr->name == name){
            return 1;
        }
        curr = curr->next;
    }
    User *new_user = malloc(sizeof(User));
    strncpy(new_user->name, name, MAX_NAME-1);
    new_user->name[MAX_NAME-1] = '\0';
    new_user -> next = NULL;

    
    curr->next = new_user;
    return 0;
}
 * Create a new user with the given name.  Insert it at the tail of the list
 * of users whose head is pointed to by *user_ptr_add.
 *
 * Return:
 *   - 0 if successful
 *   - 1 if a user by this name already exists in this list
 *   - 2 if the given name cannot fit in the 'name' array