Flutter batch commit sample

Future<void> storePushNotificationToken(String userId, String token) async {
    final batch = _firestore.batch();

    final pushTokenRef = _firestore.collection(FirestoreCollection.pushToken.path).doc(userId);
    batch.set(
      pushTokenRef,
      {'userId': userId, 'token': token},
      SetOptions(merge: true),
    );

    final pushTokenTokensRef = pushTokenRef.collection(FirestoreCollection.pushTokenTokens.path).doc();
    batch.set(
      pushTokenTokensRef,
      {'token': token, 'valid': true},
      SetOptions(merge: true),
    );

    batch.commit();
  }