anchor.diff:    ///
     /// Any part of the description that is unsupported on the current platform
     /// will be ignored.
  -  static Future<Null> setApplicationSwitcherDescription(ApplicationSwitcherDescription description) async {
  +  static Future<void> setApplicationSwitcherDescription(ApplicationSwitcherDescription description) async {
       await SystemChannels.platform.invokeMethod(
         'SystemChrome.setApplicationSwitcherDescription',
         <String, dynamic>{
  
positive.code:   /// The `orientation` argument is a list of [DeviceOrientation] enum values.
    /// The empty list causes the application to defer to the operating system
    /// default.
    static Future<Null> setPreferredOrientations(List<DeviceOrientation> orientations) async {
      await SystemChannels.platform.invokeMethod(
        'SystemChrome.setPreferredOrientations',
        _stringify(orientations),
  
negative.code:   ///
    /// On Android, the system UI cannot be changed until 1 second after the previous
    /// change. This is to prevent malware from permanently hiding navigation buttons.
    static Future<void> restoreSystemUIOverlays() async {
      await SystemChannels.platform.invokeMethod(
        'SystemChrome.restoreSystemUIOverlays',
        null,
  