About animation stop

Hello,
I would like to created a little animation :wink: I did it. It’s run correctly but how can I do to stop it if I want? please
Thank you for your help

 play() async {
     saveI=0;
     start=true;
     final Stream myStream = new Stream.periodic(Duration(milliseconds: 900));
     myStream.map((v) {
     }).take(nbr).forEach((e) async {
       await callback();
     });
   }