Function cros_async::select7

pub async fn select7<F1: Future + Unpin, F2: Future + Unpin, F3: Future + Unpin, F4: Future + Unpin, F5: Future + Unpin, F6: Future + Unpin, F7: Future + Unpin>(
    f1: F1,
    f2: F2,
    f3: F3,
    f4: F4,
    f5: F5,
    f6: F6,
    f7: F7
) -> (SelectResult<F1>, SelectResult<F2>, SelectResult<F3>, SelectResult<F4>, SelectResult<F5>, SelectResult<F6>, SelectResult<F7>)