fn inspect(_: &mut VM, self_val: Value, args: &Args2) -> VMResult {
    args.check_args_num(0)?;
    Ok(Value::string(self_val.into_module().inspect()))
}
## instance method Module#inspect
- to_s -> String
- inspect -> String

https://docs.ruby-lang.org/ja/latest/method/Module/i/inspect.html
ruruby/src/builtin/module.rs