I use this code in my __init__.py of New Words Loss:
https://github.com/otakutyrant/New-Words-Loss
FORMAT = "[%(filename)s->%(funcName)s():]%(levelname)s: %(message)s"
logging.basicConfig(format=FORMAT, level=logging.INFO)
But strangely, when I run the plugin: `calibre-debug -s; calibre-customize -b .; calibre`, all logging.info only prints levelname and message but filename and funcName, like this: INFO:root:Infering New Words Loss in 1 books.