title: 2 dots and three dots in flutter
body: <p>what does the 2 dots mean in dart like this one when you want to create a Paint:</p>
  
  <pre><code>var paint = Paint()
  ..shader = gradient.createShader(rect)
  </code></pre>
  
  <p>and the 3 dots like this sample I saw it in flutter sample</p>
  
  <pre><code>ListView(
          children: [
            ListTile(title: Text('Basics', style: headerStyle)),
            ...basicDemos.map((d) =&gt; DemoTile(d)),
            ListTile(title: Text('Misc', style: headerStyle)),
            ...miscDemos.map((d) =&gt; DemoTile(d)),
          ],
        ),
  </code></pre>