https://gist.github.com/alfrdmalr/faa012e421d9f7f60c3e6d2d32...

IIRC in one of the "what's new announcements" from the TS team included sample code to do it as well.

Edit: here is another example of doing it https://gist.github.com/kuroski/9a7ae8e5e5c9e22985364d1ddbf3...

And here is a medium article walking through the code step by step https://medium.com/@fullstack-shepherd/typescript-transformi...