-- rgxsub pattern replacement subject: global regex replace, returns text.
-- Supports backrefs $1, $2, in the replacement (Rust `regex` crate syntax).
scrub-digits s:t>t;rgxsub "\d+" "X" s
swap-pair s:t>t;rgxsub "(\w+)-(\w+)" "$2-$1" s
-- run: scrub-digits a1b22c333
-- out: aXbXcX
-- run: swap-pair hello-world
-- out: world-hello
-- run: scrub-digits nodigits
-- out: nodigits