Flutter Animation I: Background Color Transition

background_color_transition.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Background color transition',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage>
    with SingleTickerProviderStateMixin {
  AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 10),
      vsync: this,
    )..repeat();
  }

  Animatable<Color> background = TweenSequence<Color>([
    TweenSequenceItem(
      weight: 1.0,
      tween: ColorTween(
        begin: Colors.red,
        end: Colors.green,
      ),
    ),
    TweenSequenceItem(
      weight: 1.0,
      tween: ColorTween(
        begin: Colors.green,
        end: Colors.blue,
      ),
    ),
    TweenSequenceItem(
      weight: 1.0,
      tween: ColorTween(
        begin: Colors.blue,
        end: Colors.pink,
      ),
    ),
  ]);

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
        animation: _controller,
        builder: (context, child) {
          return Scaffold(
            body: Container(
              color: background
                  .evaluate(AlwaysStoppedAnimation(_controller.value)),
            ),
          );
        });
  }
}

This code is not working recent flutter version