anchor.diff:      _clearOutput();
     }
   
  -  Future showHome(RouteEnterEvent event) async {
  +  void showHome(RouteEnterEvent event) {
       // Don't auto-run if we're re-loading some unsaved edits; the gist might
       // have halting issues (#384).
       bool loadedFromSaved = false;
  
positive.code:     } else if (url.hasQuery && url.queryParameters['source'] != null) {
        Future<UuidContainer> futureGistId = dartSupportServices
            .retrieveGist(id: url.queryParameters['source']);
        await futureGistId.then((UuidContainer gistId) {
          gistLoader.loadGist(gistId.uuid).then((Gist backing) {
            editableGist.setBackingGist(backing);
            router.go('gist', {'gist': backing.id});
  
negative.code:     }
    }
  
    Stream get onChanged => file.onChanged.map((value) => value);
  }
  
  class EditorDocumentProperty implements Property {
  