It would be really cool if you could register additional custom SQL functions for use with the sqlite-utils query command - something like this:

sqlite-utils data.db 'update images set domain = extract_domain(url)' --functions '
from urllib.parse import urlparse

def extract_domain(url):
    return urlparse(url).netloc
'

Every function defined in that code block would be registered with the connection, unless the name began with an underscore.