Flutter/Dart - Difference between () {} and () => {} : <p>In Flutter/Dart the examples sometimes show fat arrow and sometimes dont.  Here are examples:</p>

<pre><code>RaisedButton(
  onPressed: () {
    setState(() {
      _myTxt = "Text Changed";
    });
  },
</code></pre>

<p>Elsewhere you see:</p>

<pre><code>void main() =&gt; runApp(MyApp());
</code></pre>
