Testing is a fundamental part of that. Sometimes you can prove by analysis, you know, just by using maths and showing this is what the system was designed to do. But the first prize is if you can run a test and say, look, we've got a controlled set of inputs,. We can measure the outputs  and we can determine from this how well it's working. And so, I'm kind of keen on this concept of testing because I think it adds a level of rigor and transparency to the scientific process.