Project lint checked and step added to config.yml

lib/base_viewmodel.dart

@@ -0,0 +1,32 @@
+import 'package:stacked/stacked.dart';
+
+import 'Utils/view_state.dart';
+
+abstract class BaseViewmodel extends BaseViewModel{
+
+  ViewState _viewState = Idle();
+  ViewState get viewState => _viewState;
+
+  void onStart() {
+    _viewState = HasStarted();
+    notifyListeners();
+  }
+
+  void onSuccess(dynamic data) {
+    _viewState = HasData(data);
+    notifyListeners();
+  }
+
+  void onError(String error) {
+    _viewState = HasError(error);
+    notifyListeners();
+  }
+
+  dynamic getData() {
+    if (viewState.runtimeType is HasData) {
+      return (viewState as HasData).data;
+    } else {
+      return null;
+    }
+  }
+}