`Converter.parse_line` doesn't remove remove trailing whitespace before comments
Converter.parse_line(" stub-addr: 220.127.116.11 # K.ROOT-SERVERS.NET.)`
which fails for obvious reasons.
In general, it is really hard to work with all the regexes and corner cases of parsing a configuration file with parser written from scratch. I dare to guess the most of real-life
unbound.conf files would not pass
converter.py in the current state.