here is mine:
program:
# Remove tags listed in tags_to_ignore
tags_to_ignore = 'danach, leicht';
list_join(':@:',
list_difference($tags, tags_to_ignore, ','), ',',
list_difference($#rreadingpool, tags_to_ignore, ','), ',')
But I like to guide you to the whole story as that may help you for your personal solution:
https://www.mobileread.com/forums/sh...d.php?t=211135
start with post 2842 upto post 2855 on page 190/191