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    use {Future, Poll, Async};
    use stream::Stream;

    /// A combinator used to temporarily convert a stream into a future.
    ///
    /// This future is returned by the `Stream::into_future` method.
    #[derive(Debug)]
    #[must_use = "futures do nothing unless polled"]
    pub struct StreamFuture<S> {
        stream: Option<S>,
    }

    pub fn new<S: Stream>(s: S) -> StreamFuture<S> {
        StreamFuture { stream: Some(s) }
    }

    impl<S> StreamFuture<S> {
        /// Acquires a reference to the underlying stream that this combinator is
        /// pulling from.
        ///
        /// This method returns an `Option` to account for the fact that `StreamFuture`'s
        /// implementation of `Future::poll` consumes the underlying stream during polling
        /// in order to return it to the caller of `Future::poll` if the stream yielded
        /// an element.
        pub fn get_ref(&self) -> Option<&S> {
            self.stream.as_ref()
        }

        /// Acquires a mutable reference to the underlying stream that this
        /// combinator is pulling from.
        ///
        /// Note that care must be taken to avoid tampering with the state of the
        /// stream which may otherwise confuse this combinator.
        ///
        /// This method returns an `Option` to account for the fact that `StreamFuture`'s
        /// implementation of `Future::poll` consumes the underlying stream during polling
        /// in order to return it to the caller of `Future::poll` if the stream yielded
        /// an element.
        pub fn get_mut(&mut self) -> Option<&mut S> {
            self.stream.as_mut()
        }

        /// Consumes this combinator, returning the underlying stream.
        ///
        /// Note that this may discard intermediate state of this combinator, so
        /// care should be taken to avoid losing resources when this is called.
        ///
        /// This method returns an `Option` to account for the fact that `StreamFuture`'s
        /// implementation of `Future::poll` consumes the underlying stream during polling
        /// in order to return it to the caller of `Future::poll` if the stream yielded
        /// an element.
        pub fn into_inner(self) -> Option<S> {
            self.stream
        }
    }

    impl<S: Stream> Future for StreamFuture<S> {
        type Item = (Option<S::Item>, S);
        type Error = (S::Error, S);

        fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
            let item = {
                let s = self.stream.as_mut().expect("polling StreamFuture twice");
                match s.poll() {
                    Ok(Async::NotReady) => return Ok(Async::NotReady),
                    Ok(Async::Ready(e)) => Ok(e),
                    Err(e) => Err(e),
                }
            };
            let stream = self.stream.take().unwrap();
            match item {
                Ok(e) => Ok(Async::Ready((e, stream))),
                Err(e) => Err((e, stream)),
            }
        }
    }

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