pub(crate) fn get_class_if_object(&self, val: Value) -> Module {
        match val.if_mod_class() {
            Some(class) => class,
            None => self.get_class(val),
        }
    }
If `self` is Class or Module, return `self`.
Otherwise, return 'real' class of `self`.
ruruby/src/globals.rs