fn start_main() -> i64 {
    let missing: result<string> = read_text_file("missing.txt");
    if (missing::ok) {
        print(missing::value);
    } else {
        print(missing::error::code + "\n");
    }
    let saved: result<unit> = write_text_file("lesson.txt", "hello\n");
    if (saved::ok) {
        let loaded: result<string> = read_text_file("lesson.txt");
        if (loaded::ok) {
            print(loaded::value);
        } else {
            print(loaded::error::code + "\n");
        }
    } else {
        print(saved::error::code + "\n");
    }
    return 0;
}