fn inspect(_: &mut VM, self_val: Value, args: &Args2) -> VMResult {
    args.check_args_num(0)?;
    let time = self_val.as_time();
    Ok(Value::string(format!("{}", time)))
}
Time#inspect -> String
https://docs.ruby-lang.org/ja/latest/method/Time/i/inspect.html
ruruby/src/builtin/time.rs