You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: is_end_stream.rs
    path of file: ./repos/phaser/phaser/vendor/http-body/tests
    
    the code of the file until where you have to start completion: use http::HeaderMap;
use http_body::{Body, SizeHint};
use std::pin::Pin;
use std::task::{Context, Poll};

struct Mock {
    size_hint: SizeHint,
}

impl Body for Mock {
    type Data = ::std::io::Cursor<Vec<u8>>;
    type Error = ();

    fn poll_data(
        self: Pin<&mut Self>,
        _cx: &mut Context<'_>,
    ) -> Poll<Option<Result<Self::Data, Self::Error>>> {
        Poll::Ready(None)
    }

    fn poll_trailers(
        self: Pin<&mut Self>,
        _cx: &mut Context<'_>,
    ) -> Poll<Result<Option<HeaderMap>, Self::Error>> {
        Poll::Ready(Ok(None))
    }

    fn si
    
fn is_end_stream_true() {
    let combos = [
        (None, None, false),
        (Some(123), None, false),
        (Some(0), Some(123), false),
        (Some(123), Some(123), false),
        (Some(0), Some(0), false),
    ];

    for &(lower, upper, is_end_stream) in &combos {
        let mut size_hint = SizeHint::new();
        assert_eq!(0, size_hint.lower());
        assert!(size_hint.upper().is_none());

        if let Some(lower) = lower {
            size_hint.set_lower(lower);
        }

        if let Some(upper) = upper {
            size_hint.set_upper(upper);
        }

        let mut mock = Mock { size_hint };

        assert_eq!(
            is_end_stream,
            Pin::new(&mut mock).is_end_stream(),
            "size_hint = {:?}",
            mock.size_hint.clone()
        );
    }
}