pub fn spawn_pooled<T, R, I, Fun, Fut>(
iter: impl IntoIterator<Item = I>,
config: Config,
fun: Fun
) -> (ChildPool<R>, Address<T>) where
Fun: FnOnce(I, Inbox<T>) -> Fut + Send + 'static + Clone,
Fut: Future<Output = R> + Send + 'static,
R: Send + 'static,
T: Send + 'static,
I: Send + 'static,
