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

    /// A stream which "fuse"s a stream once it's terminated.
    ///
    /// Normally streams can behave unpredictably when used after they have already
    /// finished, but `Fuse` continues to return `None` from `poll` forever when
    /// finished.
    #[derive(Debug)]
    #[must_use = "streams do nothing unless polled"]
    pub struct Fuse<S> {
        stream: S,
        done: bool,
    }

    // Forwarding impl of Sink from the underlying stream
    impl<S> ::sink::Sink for Fuse<S>
        where S: ::sink::Sink
    {
        type SinkItem = S::SinkItem;
        type SinkError = S::SinkError;

        fn start_send(&mut self, item: S::SinkItem) -> ::StartSend<S::SinkItem, S::SinkError> {
            self.stream.start_send(item)
        }

        fn poll_complete(&mut self) -> Poll<(), S::SinkError> {
            self.stream.poll_complete()
        }

        fn close(&mut self) -> Poll<(), S::SinkError> {
            self.stream.close()
        }
    }

    pub fn new<S: Stream>(s: S) -> Fuse<S> {
        Fuse { stream: s, done: false }
    }

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

        fn poll(&mut self) -> Poll<Option<S::Item>, S::Error> {
            if self.done {
                Ok(Async::Ready(None))
            } else {
                let r = self.stream.poll();
                if let Ok(Async::Ready(None)) = r {
                    self.done = true;
                }
                r
            }
        }
    }

    impl<S> Fuse<S> {
        /// 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
        }

        /// Acquires a reference to the underlying stream that this combinator is
        /// pulling from.
        pub fn get_ref(&self) -> &S {
            &self.stream
        }

        /// 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.
        pub fn get_mut(&mut self) -> &mut S {
            &mut self.stream
        }

        /// 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.
        pub fn into_inner(self) -> S {
            self.stream
        }
    }

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