Ruby C扩展：我怎么知道我的C代码中生成的ruby VALUE将被GC正确清理？

I'm trying to write a really small C extension. So I don't want to make a whole ruby class, with initializer, allocator, and so forth. All I want to do is add a static method to an existing class, method which will run an algorithm and return a result. Unfortunately, all documentation I find only speak about wrapping a C struct into a VALUE, but that's not my use case.I'm trying to write a really small C extension.