async fn update_folders(
session: &mut Imap,
account: &Account,
own: &[String],
gmail: bool,
dir: &Path,
room: &dyn Fn(&Path) -> Option<u64>,
progress: &mut dyn FnMut(&Progress),
cancel: &Cancel,
checker: Option<&Checker>,
update: &mut Update,
) -> Result<(), Stop>