* app_bar.dart enum AppBarLeft { none, back } enum AppBarRight { none, notify } PreferredSizeWidget buildAppBar(BuildContext context, {AppBarLeft left = AppBarLeft.none, AppBarRight right = AppBarRight.none, String title = '', double height = 56}) { return AppBar( automaticallyImplyLeading: left == AppBarLeft.none ? false : true, title: title.isEmpty ? null : Text(title), toolbarHeight: height, ..