code: def request_pick_fruit(self, req):
          
          r = random.choice(self.FRUIT + [None])
          if r is None:
              return ("fail", "No fruit.")
          delay = random.randrange(1,5)
          req.inform("Picking will take %d seconds" % delay)
  
          def pick_handler():
              self._fruit_result.set_value(r)
              req.reply("ok", r)
  
          self.ioloop.add_callback(
              self.ioloop.call_later, delay, pick_handler)
  
          raise AsyncReply
docs: Pick a random fruit.