imap inbox, how not to show mails marked Expired

[Gijs Hillenius]

I'm relearning my Gnus habits, now marking messages as expirable instead
of deleting (expunging) them. The result is an Inbox with some 20 or
more emails that I don't mind not seeing, unless I want to
expressly. These will get expunged by Gnus and then removed from disk by
Cyrus IMAP after a week.

I've been browsing the manual, but I'm going in circles. What would be
the a/key combination to hide messages that are marked (expired)? Per
group, I guess, I'm not sure I want to set it for all groups.

Thanks