> #DEBHELPER#
>
One of the first google hits:
https://manpages.debian.org/bullseye/debhelper/debhelper.7.en.html
Some debhelper commands will automatically generate parts of Debian maintainer scripts. If you want these automatically generated things included in your existing Debian maintainer scripts, then you need to add #DEBHELPER# to your scripts, in the place the code should be added. #DEBHELPER# will be replaced by any auto-generated code when you run dh_installdeb.