Method poll

tests/all/async_functions.rs:799–807

(mut self: Pin<&mut Self>, cx: &mut Context<'_>)

    type Output = (F::Output, usize);

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        match Pin::new(&mut self.future).poll(cx) {
            Poll::Pending => {
                self.yields += 1;
                Poll::Pending
            }
            Poll::Ready(e) => Poll::Ready((e, self.yields)),
        }
    }
}

pub struct PollOnce<F>(Option<F>);