int make_friends(const char *name1, const char *name2, User *head) {
    if (strcmp(name1, name2) == 0){
            return 3;
    }

    if (find_user(name1, head) == NULL || find_user(name2, head) == NULL){
            return 4;
    }

    User *user1 = find_user(name1, head);
    User **temp1 = user1->friends;
    User *user2 = find_user(name2, head);
    User **temp2 = user2->friends;
    while (temp1 != NULL){
            if (strcmp((**temp1)->name, (*user2)->name) == 0){
                    return 1;
            }
            temp1 = temp1->next;
    }

    if (**temp1 > 10 || **temp2 > 10){
            return 2;
    }
    // There are no errors and can proceed
    while (temp1->next != NULL){
            temp1 = temp1->next;
    }
    strcpy(temp1->next, user2->name);
    User *temp2 = user2->friends;
    while (temp2->next != NULL){
            temp2 = temp2->next;
    }
    strcpy(temp2->next, user1->name);
    return 0;
}



Make two users friends with each other.  This is symmetric - a pointer to
 * each user must be stored in the 'friends' array of the other.
 *
 * New friends must be added in the first empty spot in the 'friends' array.
 *
 * Return:
 *   - 0 on success.
 *   - 1 if the two users are already friends.
 *   - 2 if the users are not already friends, but at least one already has
 *     MAX_FRIENDS friends.
 *   - 3 if the same user is passed in twice.
 *   - 4 if at least one user does not exist.
 *
 * Do not modify either user if the result is a failure.
 * NOTE: If multiple errors apply, return the *largest* error code that applies.