Function forward_input_output 

pub(crate) fn forward_input_output<R>(
    input: &mut PartialBuffer<impl AsRef<[u8]>>,
    output: &mut PartialBuffer<impl AsRef<[u8]> + AsMut<[u8]>>,
    f: impl FnOnce(&mut PartialBuffer<&[u8]>, &mut WriteBuffer<'_>) -> R,
) -> R