I managed to do this on my very first job. I worked at a company where they needed to integrate data from multiple vendors into a unified schema. So, ended up building a library that could take xpath and a value and would navigate down the the path, creating missing entries along the way, then insert the value at the given location. It worked really nicely cause it let our business people just fill out a spreadsheet, and provide a csv that would get ingested. The internals of it were absolutely nightmarish though, cause I just kept kludging stuff in to accommodate for new use cases, and of course all of it was completely undocumented. After I left, I heard that at least three separate attempts were made at rewriting that nightmare, and everyone just gave up eventually. For all I know, it's still in production to this day because it became a foundational piece that nobody has any hope of understanding. 😂

That's when you wait a month and offer your consultation services at exorbitant rates