Show HN: awk commands for `union`, `intersect`, `except`, `extra`

I'm munging text and I wrote these awk commands that may be useful to other coders. Feedback welcome. union (https://github.com/sixarm/union): print lines in (A union B) intersect (https://github.com/sixarm/intersect): print lines in (A intersect B) except (https://github.com/sixarm/except): print lines in (A except B) a.k.a. (A - B) extra (https://github.com/sixarm/extra) : print lines in (A extra B) a.k.a. (B - A) Examples: $ cat 1.txt alpha bravo $ cat 2.txt alpha charlie $ union 1.txt 2.txt alpha bravo charlie $ intersect 1.txt 2.txt alpha $ except 1.txt 2.txt bravo $ extra 1.txt 2.txt charlie