I'd caution you from pulling examples from other operating systems. I started dicking around with writing an interactive pf shell earlier this year (which some

I'd caution you from pulling examples from other operating systems. I started dicking around with writing an interactive pf shell earlier this year (which somehow got me to where I am today writing an xpath parser in rust) and quickly learned that a.) the documentation is often pretty sparse especially for the API and b.) pf is all over the place (Solaris, MacOS, FreeBSD, OpenBSD, DragonFly, pfSense, etc.) but each version has some pretty significant differences. Every single one (including pfSense) has their own variant. From what I can tell FreeBSD's taken bigger steps to sync up with OpenBSD than the rest, certainly bigger than pfSense.