int create_user(const char *name, User **user_ptr_add) {
    if (strlen(name) > MAX_NAME - 1) {
        return 2;
    }
    User *new_user = malloc(sizeof(User));
    strcpy(new_user->name, name);
    new_user->next = NULL;
    User *curr = *user_ptr_add;
    if (curr == NULL) {
        curr = new_user;
    } else {
        while (curr->next != NULL) {
        if (curr->name == name) {
            return 1;
        }
        curr = curr->next;
    }
    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
 *       (don't forget about the null terminator)
 */