in coreaudio-sys-utils/src/dispatch.rs [363:368]
fn sync_return_value() {
let q = Queue::new("Test queue");
assert_eq!(q.run_sync(|| 42), Some(42));
assert_eq!(q.run_final(|| "foo"), Some("foo"));
assert_eq!(q.run_sync(|| Ok::<(), u32>(())), None);
}