The application's top-level routing table.
When a named route is pushed with Navigator.pushNamed, the route name is looked up in this map. If the name is present, the associated WidgetBuilder is used to construct a CupertinoPageRoute that performs an appropriate transition, including Hero animations, to the new route.
If the app only has one page, then you can specify it using home instead.
final Map<String, WidgetBuilder> routes