Function handle_client 

async fn handle_client<S>(
    socket: &mut ClientSocket<S>,
    state: &Arc<TransportState>,
    watching: &mut Watching,
    holds: &mut Holds<'_>,
    updates: &mut Option<(UnboundedReceiver<SeatUpdate>, bool)>,
    dictate: &mut Streaming,
    viewers: &mut Viewers,
    reads: &mut Reads,
    arrival: Arrival,
    msg: Message,
) -> Result<()>
where
    S: Sink<Message, Error = Error> + Unpin + Send,

Answer one client message.