Function accept_loop 

pub async fn accept_loop<F>(
    listener: UnixListener,
    on_message: F,
    shutdown: Receiver<()>,
)
where
    F: Fn(ClientMessage, UnboundedSender<ServerMessage>) + Clone + Send + 'static,

Accept connections on the given UnixListener until shutdown is signalled.

Each connection is handled in a separate task. For each incoming ClientMessage, calls on_message(msg, reply_tx) where reply_tx is the per-connection sender for streaming ServerMessages back.