anchor.diff:      var difference = DateTime.now().difference(DateTime.parse(previousTime)).inSeconds;
       print(difference);
       if (difference > 10) {
  -      beaconUuid = Uuid().v4();
  +      changeUUID();
         prefs.setString('previousTime', DateTime.now().toString());
       }
   
     }
   
  -  void startBroadcast () {
  -    //start beacon broadcasting
  -    //if (isBroadcasting)
  -    //  return;
  +  void _startBroadcast () {
  +    if (_isAdvertising)
  +      return null;
   
       beaconBroadcast
  -        .setUUID(beaconUuid)
  -        .setMajorId(1)
  -        .setMinorId(100)
  -        .setIdentifier('com.example.myDevice')
  -        .setLayout(BeaconBroadcast.ALTBEACON_LAYOUT)
  -        .start();
  +      .setUUID(beaconUuid)
  +      .setMajorId(1)
  +      .setMinorId(100)
  +      .setIdentifier('com.example.myDevice')
  +      .setLayout(BeaconBroadcast.ALTBEACON_LAYOUT)
  +      .start();
   
       print(beaconUuid);
  -    setState(() {
  -      broadcastingState = "Currently broadcasting";
  -    });
     }
   
  -  void stopBroadcast () {
  -    // stop beacon broadcasting
  -    //if (!isBroadcasting)
  -    //  return;
  -
  -    beaconBroadcast.stop();
  -    setState(() {
  -      broadcastingState = "Currently not broadcasting";
  -      beaconUuid = "null";
  -    });
  -  }
  +  void _stopBroadcast () => beaconBroadcast.stop();
   
     void changeUUID () {
       beaconUuid = Uuid().v4();
  -    print(beaconUuid);
  +    beaconUuid = "00000000" + beaconUuid.substring(8);
       setState(() {});
     }
   
  
positive.code: 
      SharedPreferences prefs = await SharedPreferences.getInstance();
      prefs.setString('uuid', beaconUuid);
      //uuidTimer.cancel();
      print("Exit beacon");
    }
  
    void checkTime () async {
  
negative.code:       });
      });
  
      _isAdvertisingSubscription = beaconBroadcast.getAdvertisingStateChange().listen((isAdvertising) {
        setState(() {
          _isAdvertising = isAdvertising;
        });
      });
    }
  
    @override
  