//1- Subscribe user device to topic
		FCMSubscriptionManager.getInstance(this).subscribeToTopic("TopicName");
	//2- Unsubscribe user device from topic 
	        FCMSubscriptionManager.getInstance(this).unsubscribeFromTopic("TopicName");
	//3- Unsubscribe user device to list of topics 
		FCMSubscriptionManager.getInstance(this).unsubscribeAll();
	//4- Subscribe user device from all subscribed topics
		FCMSubscriptionManager.getInstance(this).subscribeListOfTopics(listOfTopics) //listOfTopics ( list of string )

	// at Activity 
           FCMPullNotificationManager manager = FCMPullNotificationManager.getInstance(this);
	// at Fragment 
	   FCMPullNotificationManager manager = FCMPullNotificationManager.getInstance(getContext());

	// make to activity or fragment implement IPullFCMCallback and use this line. 
		(Like YourActivity implement IPullFCMCallback) 
	 	manager.registerListener( this);
	// or make an anonymous class 
		 manager.registerListener(new IPullFCMCallback() {
		    @Override
		    public void onMessageReceived(RemoteMessage message) {
			// it will be called reveive notification for FCM 
		    }

		    @Override
		    public void onDeviceRegistered(String tokenId) {
			// it will be called when user device register for first time (first run application) 
		    }

		    @Override
		    public void onErrorHappened(String errorMessage) {
			// it will be called when something wrong happened 
		    }
        });

	// just tell manager that you will handle notification
 	manager.autoLaunchNotification(builder);
	// builder!? 
	// build a Notificationbuilder that has all properties you need , that will affect on apprance and properties of notification 
 	 NotificationBuilder builder = new NotificationBuilder(this) // this--> Context, if you will use fragment ,use getContext()
	// should set intent that has the launched activity (
	 .setContentIntent(new Intent(getApplicationContext(), YourActivity.class))
	// icon notification that will be at foreground ONLY, 
	// at background the app icon will be in notification that's handle by firebase
	 .setNotificationIcon(id)
	// make your notification auto cancelled 
	 .setAutoCancel(true)
	// make sound of notification is defualt sound of device 
	.setDefaultSound()
	// set custom sound for notification (foreground and background)
	.setCustomSound(customSound)
	// customize notification title 
	.setNotificationTitle("Your custom title")
	// customize notification Message
	.setNotificationMessage("Your cutsom messages ")

	// initiate and send your server key 
    	FCMPushNotificationManager manager = FCMPushNotificationManager.getInstance(serverKey);

	// make to activity or fragment implement IPushFCMCallback and use this line. 
		(Like YourActivity implement IPushFCMCallback) 
	 	manager.registerListener( this);
	// or make an anonymous class 
		manager.setPushFCMCallback(new IPushFCMCallback() {
                    @Override
                    public void onPushNotificationSuccess() {
                       // on pushinh notification  
                    }

                    @Override
                    public void onError(String errorMessage) {
                       // on can't push notification  
                    }
                });

	// You can notify through 4 ways as following 
	
	//1- Notify group of people subscribed to some topic
	   manager.notifyByTopic("Title", "Message","TopicName")
	//2-Notify list of groups of people subscribed to some topics
	   manager.notifyByTopics("Title", "Message",ListOfTopics) //ListOfTopics --> List of String 
	//3-Notify just one person through his/her TokenID
	   manager.notifyByToken("Title", "Message",userToken)
	//4-Notify just some persons through their TokenID
	   manager.notifyByToken("Title", "Message",listOfTokensID) 
	 //(Optional) you can send extra data with notification    
         .addExtraData(data).send(); //data --> Map<Stirng,Stirng>
	 // To apply the action 
	 .send();