Remove unwraps and unimplemented! calls and propagate them properly. This [type ](https://github.com/MSleepyPanda/explain-rs/blob/dc15605bd6f481e66806af61b5fdfe054fd0fd23/src/explain.rs#L12-L15)is a stub in prep for this. Though unimplemented is the logically correct choice, we can still produce intermediate results, which can be outputted.
