Nice, thanks! Could you publish the code on GitHub as well, so people can collaborate on it?
And also: you should use is.convert a) if you are also passing in index and parent, and b) reusing it, with this setup is is better.

@wooorm Oh goodness! I have no idea why my index.js file was not included in git commits! 😱 I'll be sure to push that. I am using is.convert, however

The index.js and index.test.js files have been added to the repo. Sorry once again, t'was an autogenerated gitignore that I forgot about

Sweet!

I am using is.convert, however

Right! What I meant was that, the way you are using is.convert currently, it’s better to use is.
If you want to use is.convert, you should a) convert it in flatFilter, b) pass the new converted function into flatFilterGeneric, and c) make sure that that converted functions get node, index, parent when called.
a) and b) would make it more performant, c) would make sure the user-provided test works exactly the same in your project as all other unist utilities

Oh, I understand better now! I'll be sure to follow up in the library to include the changes as you mentioned. Thanks for the review! 😁

Sweet! Thanks & congrats on your first unist utility! ✨