simple widget tree with managing data with each

lib/product_manager.dart

@@ -0,0 +1,44 @@
+import 'package:flutter/material.dart';
+
+import './products.dart';
+
+class ProductManager extends StatefulWidget {
+  final String startingProduct;
+
+  ProductManager(this.startingProduct);
+
+  @override
+  State<StatefulWidget> createState() {
+    return _ProductManagerState();
+  }
+}
+
+class _ProductManagerState extends State<ProductManager> {
+  List<String> _products = [];
+
+  @override
+  void initState() {
+    super.initState();
+    _products.add(widget.startingProduct);    
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Column(
+      children: [
+        Container(
+          margin: EdgeInsets.all(10),
+          child: RaisedButton(
+            onPressed: () {
+              setState(() {
+                _products.add('Advanced Food Tester');
+              });
+            },
+            child: Text('Click Me!'),
+          ),
+        ),
+        Products(_products),
+      ],
+    );
+  }
+}