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    use core::fmt;
    use core::pin::Pin;
    use futures_core::future::{Future, TryFuture};
    use futures_core::ready;
    use futures_core::stream::TryStream;
    use futures_core::task::{Context, Poll};
    use pin_project_lite::pin_project;

    pin_project! {
        /// Future for the [`try_for_each`](super::TryStreamExt::try_for_each) method.
        #[must_use = "futures do nothing unless you `.await` or poll them"]
        pub struct TryForEach<St, Fut, F> {
            #[pin]
            stream: St,
            f: F,
            #[pin]
            future: Option<Fut>,
        }
    }

    impl<St, Fut, F> fmt::Debug for TryForEach<St, Fut, F>
    where
        St: fmt::Debug,
        Fut: fmt::Debug,
    {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            f.debug_struct("TryForEach")
                .field("stream", &self.stream)
                .field("future", &self.future)
                .finish()
        }
    }

    impl<St, Fut, F> TryForEach<St, Fut, F>
    where St: TryStream,
          F: FnMut(St::Ok) -> Fut,
          Fut: TryFuture<Ok = (), Error = St::Error>,
    {
        pub(super) fn new(stream: St, f: F) -> Self {
            Self {
                stream,
                f,
                future: None,
            }
        }
    }

    impl<St, Fut, F> Future for TryForEach<St, Fut, F>
        where St: TryStream,
              F: FnMut(St::Ok) -> Fut,
              Fut: TryFuture<Ok = (), Error = St::Error>,
    {
        type Output = Result<(), St::Error>;

        fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
            let mut this = self.project();
            loop {
                if let Some(fut) = this.future.as_mut().as_pin_mut() {
                    ready!(fut.try_poll(cx))?;
                    this.future.set(None);
                } else {
                    match ready!(this.stream.as_mut().try_poll_next(cx)?) {
                        Some(e) => this.future.set(Some((this.f)(e))),
                        None => break,
                    }
                }
            }
            Poll::Ready(Ok(()))
        }
    }