Code are copied from :
- https://github.com/centrifugal/centrifuge-dart/blob/master/example/flutter_app/lib/main.dart
 - https://github.com/nitishk72/flutter_app_local_notification/blob/master/lib/main.dart
 
- Centrifugo Install here
 - Golang Install here
 
- git clone https://github.com/codenoid/flutter-centrifugo-push-notification
 - run centrifugo with config 
centrifugo --client_insecure --config=centrifugo-config.json - Customize centrifugo url (flutter and fcpn_server)
 - cd to 
fcpn_serverthengo run . - run your flutter app, Connect then subscribe
 - send your notification via fcpn_server (point 4)
 - congrats, you have push notification without FCM