I agree, but as I tried to make clear in the article, I've only tried to make the code as generalized as possible. For the memoize class for example, you would

I agree, but as I tried to make clear in the article, I've only tried to make the code as generalized as possible. For the memoize class for example, you wouldn't care. For the safe class, you'd definitely write in more exceptions to handle more issues your source might have. In this process, you'd be writing the proper method signature in. You're right though, I should have made that clearer.