pub fn concurrent_counter_service<'a>(
increment_requests: KeyedStream<u32, (), Process<'a, CounterServer>>,
get_requests: KeyedStream<u32, (), Process<'a, CounterServer>>,
) -> (KeyedStream<u32, (), Process<'a, CounterServer>>, KeyedStream<u32, usize, Process<'a, CounterServer>>)