def server [channel:^Int] =

     channel?i = (channel!(i+1) | server!channel)


def client [channel:^Int i:Int lk:^[]] =
            
       lk?[] = (channel!i

               | channel?n = (printi!n | lk![])


run( new ch1:^Int
     new lock:^[]
     
     (server!ch1

      | lock![]

      | client![ch1 3 lock]

      | client![ch1 4 lock] ) )