(This is a curious-about-our-personal-differences comment rather than a not-sure-about-merging-it comment.) Given all the subclasses & non-subclasses which support a "[]" operator, I haven't considered checking an object's class in Ruby. Also, I don't think I'd usually validate an object which I created in the same source file as the check. (The input to "valid_result?" is a Hash created 30 lines up.)