17
15

18
16

class _FadeInDemoState extends State<FadeInDemo> {

17

+
              double opacity = 0.0;

18

19
19

@override

20
20

Widget build(BuildContext context) {

21
21

return Column(children: <Widget>[

@@ -28,6 +28,8 @@

28
28

),

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29

onPressed: () => {}),

30
30

AnimatedOpacity(

31

+
                    duration: const Duration(seconds: 3),