int create_user(const char *name, User **user_ptr_add) {
    if (strlen(name) > MAX_NAME - 1) {
        return 2;
    }

    if (*user_ptr_add == NULL) {
        User *user = malloc(sizeof(User));
        strcpy(user->name, name);
        *user_ptr_add = user;
        return 0;
    }

    User *curr = *user_ptr_add;
    while (curr->next != NULL) {
        if(strcmp(curr->name, name) == 0) {
            return 1;
        }
        curr = curr->next;
    }
    User *user = malloc(sizeof(User));
    strcpy(user->name, name);
    curr->next = 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)