anchor.diff:    @override
     void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) {
       super.didPush(route, previousRoute);
  -    if (route is PageRoute) {
  +    if (routeFilter(route)) {
         _sendScreenView(route);
       }
     }
  
positive.code: /// );
  /// ```
  ///
  /// You can also track screen views within your [PageRoute] by implementing
  /// [PageRouteAware] and subscribing it to [FirebaseAnalyticsObserver]. See the
  /// [PageRouteObserver] docs for an example.
  class FirebaseAnalyticsObserver extends RouteObserver<PageRoute<dynamic>> {
    /// Creates a [NavigatorObserver] that sends events to [FirebaseAnalytics].
    ///
    /// When a route is pushed or popped, [nameExtractor] is used to extract a
  
negative.code:   @override
    void didReplace({Route<dynamic>? newRoute, Route<dynamic>? oldRoute}) {
      super.didReplace(newRoute: newRoute, oldRoute: oldRoute);
      if (newRoute != null && routeFilter(newRoute)) {
        _sendScreenView(newRoute);
      }
    }
  