code: def start_service(addr, n, authenticator):
      
  
      s = Subscriber(addr, authenticator=authenticator)
  
      def do_something(line):
          pass
  
      s.subscribe('test', do_something)
  
      started = time.time()
      for _ in range(n):
          s.process()
      s.socket.close()
      duration = time.time() - started
  
      print('Subscriber service stats:')
      util.print_stats(n, duration)
      return
docs: Start a service