title: Find nested foreach index number
body: <p>I'm trying to find index number in a nested foreach. For example, I'm trying to do this:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;!-- ko foreach:array1 --&gt;
      &lt;!-- ko foreach:array2 --&gt;(this index)
          &lt;!-- ko foreach:array3 --&gt;
              &lt;!-- ko foreach:array4 --&gt;
                  ----( i want index of foreach array2 in here...)
              &lt;!-- /ko --&gt;
          &lt;!-- /ko --&gt;
      &lt;!-- /ko --&gt;
  &lt;!-- /ko --&gt;     
  </code></pre>
  
  <p>I tried with <code>$parentContext.$index()</code>, with which I'm able to find array index of 1 level of nested foreach, but not more than 1 level.</p>
  
  <p>Please help me to find correct binding context for the above scenario.</p>