docs: function applyNewVisibility( newVisibility ) {
        if( $scope.model.areaShowing === newVisibility ) {
           return Promise.resolve();
        }
  
        visibilityIsChanging = true;
        return publishVisibilityFlag( newVisibility )
           .then( publishAreaVisibility )
           .then( () => {
              $scope.model.areaShowing = newVisibility;
              visibilityIsChanging = false;
           } );
     }