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    use core::pin::Pin;
    use futures_core::ready;
    use futures_core::stream::{FusedStream, Stream};
    use futures_core::task::{Context, Poll};
    #[cfg(feature = "sink")]
    use futures_sink::Sink;
    use pin_project_lite::pin_project;

    pin_project! {
        /// Stream for the [`fuse`](super::StreamExt::fuse) method.
        #[derive(Debug)]
        #[must_use = "streams do nothing unless polled"]
        pub struct Fuse<St> {
            #[pin]
            stream: St,
            done: bool,
        }
    }

    impl<St> Fuse<St> {
        pub(super) fn new(stream: St) -> Self {
            Self { stream, done: false }
        }

        /// Returns whether the underlying stream has finished or not.
        ///
        /// If this method returns `true`, then all future calls to poll are
        /// guaranteed to return `None`. If this returns `false`, then the
        /// underlying stream is still in use.
        pub fn is_done(&self) -> bool {
            self.done
        }

        delegate_access_inner!(stream, St, ());
    }

    impl<S: Stream> FusedStream for Fuse<S> {
        fn is_terminated(&self) -> bool {
            self.done
        }
    }

    impl<S: Stream> Stream for Fuse<S> {
        type Item = S::Item;

        fn poll_next(
            self: Pin<&mut Self>,
            cx: &mut Context<'_>,
        ) -> Poll<Option<S::Item>> {
            let this = self.project();

            if *this.done {
                return Poll::Ready(None);
            }

            let item = ready!(this.stream.poll_next(cx));
            if item.is_none() {
                *this.done = true;
            }
            Poll::Ready(item)
        }

        fn size_hint(&self) -> (usize, Option<usize>) {
            if self.done {
                (0, Some(0))
            } else {
                self.stream.size_hint()
            }
        }
    }

    // Forwarding impl of Sink from the underlying stream
    #[cfg(feature = "sink")]
    impl<S: Stream + Sink<Item>, Item> Sink<Item> for Fuse<S> {
        type Error = S::Error;

        delegate_sink!(stream, Item);
    }