postinst is in python3-html2text 2018.1.9-1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | #!/bin/sh
set -e
case "$1" in
    configure)
        update-alternatives --install /usr/bin/html2markdown html2markdown \
                                      /usr/bin/html2markdown.py3 10 \
                            --slave /usr/share/man/man1/html2markdown.1.gz \
                                    html2markdown.1.gz \
                                    /usr/share/man/man1/html2markdown.py3.1.gz
    ;;
    abort-upgrade|abort-remove|abort-deconfigure)
    ;;
    *)
        echo "postinst called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac
# Automatically added by dh_python3:
if which py3compile >/dev/null 2>&1; then
	py3compile -p python3-html2text -V 3.2-
fi
# End automatically added section
exit 0
# vi: set et:
 |