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    use super::assert_stream;
    use core::marker::PhantomData;
    use core::pin::Pin;
    use futures_core::stream::{FusedStream, Stream};
    use futures_core::task::{Context, Poll};

    /// Stream for the [`empty`] function.
    #[derive(Debug)]
    #[must_use = "streams do nothing unless polled"]
    pub struct Empty<T> {
        _phantom: PhantomData<T>
    }

    /// Creates a stream which contains no elements.
    ///
    /// The returned stream will always return `Ready(None)` when polled.
    pub fn empty<T>() -> Empty<T> {
        assert_stream::<T, _>(Empty {
            _phantom: PhantomData
        })
    }

    impl<T> Unpin for Empty<T> {}

    impl<T> FusedStream for Empty<T> {
        fn is_terminated(&self) -> bool {
            true
        }
    }

    impl<T> Stream for Empty<T> {
        type Item = T;

        fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<Self::Item>> {
            Poll::Ready(None)
        }

        fn size_hint(&self) -> (usize, Option<usize>) {
            (0, Some(0))
        }
    }

    impl<T> Clone for Empty<T> {
        fn clone(&self) -> Self {
            empty()
        }
    }