This is a much harder question. Also much more risky -- now you need to affect multiple interconnected systems and pile on side effects. I'm sure there are an i

This is a much harder question. Also much more risky -- now you need to affect multiple interconnected systems and pile on side effects. I'm sure there are an infinite class of possible treatments that if produced in your body, would render it incompatible with being alive (or human). Imagine you need to make Excel export csv documents with dots instead of commas, and there is no easy option to toggle. The app was grown, not designed, so same commas are used in all kinds of other places in the output and in memory and even in the byte code and even in processor cache buffers. Only sane option is to add some post-processing.