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    use pin_project_lite::pin_project;
    use std::future::Future;
    use std::pin::Pin;
    use std::task::{Context, Poll};

    pin_project! {
        /// Future for the [`unconstrained`](unconstrained) method.
        #[must_use = "Unconstrained does nothing unless polled"]
        pub struct Unconstrained<F> {
            #[pin]
            inner: F,
        }
    }

    impl<F> Future for Unconstrained<F>
    where
        F: Future,
    {
        type Output = <F as Future>::Output;

        cfg_coop! {
            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
                let inner = self.project().inner;
                crate::coop::with_unconstrained(|| inner.poll(cx))
            }
        }

        cfg_not_coop! {
            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
                let inner = self.project().inner;
                inner.poll(cx)
            }
        }
    }

    /// Turn off cooperative scheduling for a future. The future will never be forced to yield by
    /// Tokio. Using this exposes your service to starvation if the unconstrained future never yields
    /// otherwise.
    ///
    /// See also the usage example in the [task module](index.html#unconstrained).
    pub fn unconstrained<F>(inner: F) -> Unconstrained<F> {
        Unconstrained { inner }
    }