Yes, making sure the program does what you want. Which is already part of the existing software development life cycle. Just as using natural language to specify work already is: It's where things start and return to over and over throughout any project. Further: LLM's frequently understand what I want better than other developers. Sure, lots of times they don't. But they're a lot better at it than they were 6 months ago, and a year ago they barely did so at all save for scripts of a few dozen lines.