title: Error: The class 'SingleTickerProviderStateMixin' can't be used as a mixin because it extends a class other than Object
body: <p>Just learning flutter Animation. using with <code>SingleTickerProviderStateMixin</code> IDE giving me this error : </p>
  
  <blockquote>
    <p>The class 'SingleTickerProviderStateMixin' can't be used as a mixin because
    it extends a class other than Object</p>
  </blockquote>
  
  <p><strong>My code:</strong> </p>
  
  <pre><code>  import 'package:flutter/material.dart';
  
    class AnimationControllerOutputBody extends StatefulWidget with  {
      @override
      _AnimationControllerOutputBodyState createState() =&gt;
          new _AnimationControllerOutputBodyState();
    }
  
    class _AnimationControllerOutputBodyState extends State&lt;AnimationControllerOutputBody&gt; with SingleTickerProviderStateMixin {
  
      AnimationController animation;
  
      @override
      void initState() {
        super.initState();
        animation = new AnimationController(
          vsync: this,
          duration: new Duration(seconds: 3),
        );
        animation.addListener(() {
          this.setState(() {});
        });
      }
  
      @override
      Widget build(BuildContext context) {
        return new GestureDetector(
          child: new Center(
            child: new Text(
              animation.isAnimating
                  ? animation.value.toStringAsFixed(3)
                  : "Tap me!",
              style: new TextStyle(
                fontSize: 50.0,
              ),
            ),
          ),
          onTap: () {
            animation.forward(from: 0.0);
          },
        );
      }
  
      @override
      void dispose() {
        animation.dispose();
        super.dispose();
      }
    }
  </code></pre>
  
  <p><strong>What's my problem in code?</strong></p>