Given a publication (created via (async/pub …)) is there a way to get hold of all subscribing channels for a given topic?

Another, related question: Is there a way to close the subscribing channel when it is unsubscribed from a pub?

The problem is that I’m using (unsub-all pub topic) so I don’t have the subscribing channels in scope.. but I would like to close them. I don’t want to close the publication channel (this would close the sub chans) because I’m still subscribed to other topics of interest

I can work around it by keeping track of the channels separately.. but the way I’ve set it up right now is quite elegant (except for this issue)