title: Listview widget yii2, how to change the index value
body: <p>As you can use a index value inside the view when using a listview widget I wanted to change this index value as I use the same view on different places, so not every element that I use have the same index on the pages.</p>
  
  <p>somepage.php</p>
  
  <pre><code>echo ListView::widget([
      'summary' =&gt; false,
      'viewParams' =&gt; [
          'url' =&gt; '',
      ],
  
      'index' =&gt; 'index + 4',//the idea
  
      'options' =&gt; [
              'class' =&gt; 'xxxx',
      ],
      'itemOptions'=&gt; [
          'class' =&gt; 'xxxx',
      ],
      'itemView' =&gt; '@frontend/views/product/_item_product_small',
      'dataProvider' =&gt; $provider,
  ]);
  </code></pre>
  
  <p>frontend/views/product/_item_product_small.php</p>
  
  <pre><code> &lt;div data-index="&lt;?=$index?&gt;"&gt;
    // content
   &lt;/div&gt;
  </code></pre>