Do you have to be sad to be funny? You’ll have to sit through a slew of micro-anecdotes and shop talk before you get any answers from this choppy documentary – longer than any decent comic would defer a punchline. It’s stitched together from what look like two-minute hotel-room interviews with well-known funny people (including Tom Hanks, Amy Schumer, Steve Coogan, Judd Apatow) and longer talks with less well-known ones. There are occasional moments of insight or comedy, such as Christopher Guest demonstrating his teacher-baiting ventriloquism, but the attention-deficit, topic-by-topic format becomes tiresome, added to which director Kevin Pollak has an annoying habit of interrupting interviewees with gags of his own – surely a breach of the comedians’ code?