[Question] How to chain sourcemaps?

[Tal500]

I'm sorry to post this as an issue, there is no discussions page here, but you may view this as a "feature request".

Assuming you have two preprocessors A and B, each of them takes the source code and outputs a pair of an output code and a sourcemap.

You now take some sourcecode, and preprocess it via A. You then take the resulted output, and preprocess it via B.

How can you chain the sourcemap generated by A and B, in the logical sense, to the final output? Is this something that is done somehow by this library? I am sure Svelte do this for its preprocessors, don't know how however.