to me 'dbc' didn't make much sense, does that abbreviate "db connection"?. 'db' itself is clean-enough and long-enough. I'm not able to find anything more clear than that.

we can either use a global pylint setting:
good-names= ...,db

or think of how to rename: thedb? db_? or just ```col = conn[self.dbname][self.dbcoll]```