What should a librarian do while someone’s stuttering?

What should a librarian do while someone’s stuttering? I work in a busy university library and speak to students with stutters occasionally. While I wait for them to speak, what’s generally the most comfortable way to behave? Should I keep eye contact and smile (smile with my eyes now we’re wearing masks) or keep a straight face? Should I stay still so they know I’m concentrating, or continue sorting out their things on the desk - like their library card or stamping books etc so they feel less pressure? I imagine it’s different for everyone but these interactions are usually pretty far apart, so it’s not like I build relationships with each student. Thank you for any general help you can provide! Edit: I’m surprised and sad that many of you have such bad experiences. These staff you come across must be bad at their jobs. I think I’ve been mostly doing the right thing, I would never interrupt, but I have unconsciously switched what I was doing (faffing/eye contact) while I wait - I’ll stop that. Also sad that some of you sense the non-stutterer being impatient. Stutterers don’t bother/ruffle me or my colleagues in the slightest in terms of emotion - the only reason I thought about it on this occasion for more than 2 seconds is because I happened to get 3 stutterers in a row and thought what a crazy coincidence. And I just wanted to know how to make them feel comfortable, not cure/hurry their actual stuttering!