Agreed. It's also instructive to look at how C extensions are written for the CPython. I wouldn't necessarily expect a demo; but not mentioning it at all seems

Agreed. It's also instructive to look at how C extensions are written for the CPython. I wouldn't necessarily expect a demo; but not mentioning it at all seems like it could lead readers down a path where they choose the "most performant" option presented (FFI + ctypes). The post has a "To go further:" link section where even a quick link to PyO3 would go a long way. So I thought I'd mention the downsides and an alternative on HN.