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import 'package:flutter/material.dart';

@@ -18,7 +16,12 @@

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@override

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void initState() {

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super.initState();

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controller = AnimationController();

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+
                controller = AnimationController(

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+
                  vsync: this, // the SingleTickerProviderStateMixin

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+
                  duration: const Duration(seconds: 1),

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+
                  lowerBound: 0,

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+
                  upperBound: 100,