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    use std::prelude::v1::*;
    use std::any::Any;
    use std::panic::{catch_unwind, UnwindSafe, AssertUnwindSafe};

    use {Future, Poll, Async};

    /// Future for the `catch_unwind` combinator.
    ///
    /// This is created by the `Future::catch_unwind` method.
    #[derive(Debug)]
    #[must_use = "futures do nothing unless polled"]
    pub struct CatchUnwind<F> where F: Future {
        future: Option<F>,
    }

    pub fn new<F>(future: F) -> CatchUnwind<F>
        where F: Future + UnwindSafe,
    {
        CatchUnwind {
            future: Some(future),
        }
    }

    impl<F> Future for CatchUnwind<F>
        where F: Future + UnwindSafe,
    {
        type Item = Result<F::Item, F::Error>;
        type Error = Box<Any + Send>;

        fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
            let mut future = self.future.take().expect("cannot poll twice");
            let (res, future) = catch_unwind(|| (future.poll(), future))?;
            match res {
                Ok(Async::NotReady) => {
                    self.future = Some(future);
                    Ok(Async::NotReady)
                }
                Ok(Async::Ready(t)) => Ok(Async::Ready(Ok(t))),
                Err(e) => Ok(Async::Ready(Err(e))),
            }
        }
    }

    impl<F: Future> Future for AssertUnwindSafe<F> {
        type Item = F::Item;
        type Error = F::Error;

        fn poll(&mut self) -> Poll<F::Item, F::Error> {
            self.0.poll()
        }
    }

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