In celebration of its 10th year as a volunteer-run nonprofit, the Grand Illusion Cinema in the University District has a treat for its audiences: “The Thin Man” (1934) and its sequel “After the Thin Man” (1936) will both play nightly, Friday through Tuesday, in 35mm. If you haven’t seen either of these sparkling screwball/caper classics, you’ve been missing something — “The Thin Man” would easily be on my top ten list of all-time favorite films, if I ever made such a thing, and “After” (which picks up immediately where the first one left off) is almost as good. William Powell plays Nick Charles, the unflappable detective created by Dashiell Hammett; Myrna Loy his impossibly clever wife Nora. Together, along with their dog Asta, they define screen chemistry, and have a ridiculous amount of fun doing it. Here’s an early scene — and a great one — from “The Thin Man,” introducing the trio.