test sieve plugin(?) development

Say for testing purposes I would like to add sender email addresses to a database file (eg gdbm) per user. How would I go about doing this?

Do I need to create something like in https://github.com/dovecot/pigeonhole/tree/src/lib-sieve/plugins

Or can I just create a go binary, and parse data to it? Is there not something like a hello world example for this?