Function split_mpsc 

pub fn split_mpsc(
    shared: &SharedLayoutCell,
) -> Result<(MpscProducer, MpscConsumer), Error>

Create MPSC producer/consumer handles over a shared layout.

Returns Err if the region is not initialized or is not v1-compatible.

The returned handles borrow the region by raw pointer; the caller must keep the underlying SharedLayout alive (and mapped) for as long as the handles are used.