Add " around all variable values.

examples/room-bot.ts

@@ -219,7 +219,7 @@ bot
             const topic = await dingRoom.topic()
             log.info('Bot', 'onMessage: sender has already in dingRoom')
             dingRoom.say('no need to ding again, because you are already in ding room', from)
-            from.say(`I found you have joined in room ${topic}!`)
+            from.say(`I found you have joined in room "${topic}"!`)
             // sendMessage({
             //   content: 'no need to ding again, because you are already in ding room'
             //   , to: sender