#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]pubenumRoutePopDisposition{// Pop the route.
// If Route.willPop returns pop then the back button will actually pop the current route.
Pop =0,// Do not pop the route.
// If Route.willPop returns doNotPop then the back button will be ignored.
DoNotPop =1,// Delegate this to the next level of navigation.
// If Route.willPop returns bubble then the back button will be handled by the SystemNavigator, which will usually close the application.
Bubble =2,}implDefault forRoutePopDisposition{fndefault()->Self{Self::Pop
}}