anchor.diff:    ///
     /// Returns null if the given context is not associated with a modal route.
     ///
  +  /// {@tool snippet}
  +  ///
     /// Typical usage is as follows:
     ///
     /// ```dart
  -  /// ModalRoute route = ModalRoute.of(context);
  +  /// ModalRoute<int>? route = ModalRoute.of<int>(context);
     /// ```
  +  /// {@end-tool}
     ///
     /// The given [BuildContext] will be rebuilt if the state of the route changes
     /// while it is visible (specifically, if [isCurrent] or [canPop] change value).
  
positive.code:   ///       child: child, // child is the value returned by pageBuilder
    ///     );
    ///   },
    /// );
    /// ```
    ///
    /// We've used [PageRouteBuilder] to demonstrate the [buildTransitions] method
    /// here. The body of an override of the [buildTransitions] method would be
    /// defined in the same way.
    ///
    /// When the [Navigator] pushes a route on the top of its stack, the
    /// [secondaryAnimation] can be used to define how the route that was on
  
negative.code: 
    /// Enables this route to veto attempts by the user to dismiss it.
    ///
    /// {@tool snippet}
    /// This callback is typically added using a [WillPopScope] widget. That
    /// widget finds the enclosing [ModalRoute] and uses this function to register
    /// this callback:
  