updated project style guidelines

lib/model/dataHolder.dart

@@ -6,19 +6,17 @@ import '../api/apiResponse.dart';
 
 abstract class DataHolder extends ChangeNotifier {
 
-  CollectionRef storage(String path) {
-    return Localstore.instance.collection(path);
-  }
+  CollectionRef storage(String path) => Localstore.instance.collection(path);
 
   void run();
   List<ApiResponse?> properties();
 
   bool primaryLoading() {
     // log("${toString()} ${properties().map((e) => e != null ? "1" : "0").join(", ")}");
-    for(ApiResponse? element in properties()) {
+    for(var element in properties()) {
       if(element == null) return true;
     }
     return false;
     //return properties().where((element) => element != null).isEmpty;
   }
-}
+}