Adding class as per LI postion
<p>I have below markup,</p>

<pre><code>&lt;ul&gt;
&lt;li&gt;1&lt;/li&gt; //light BG
&lt;li&gt;2&lt;/li&gt;
&lt;li&gt;3&lt;/li&gt;
&lt;li&gt;4&lt;/li&gt; //light BG
&lt;li&gt;5&lt;/li&gt;
&lt;li&gt;6&lt;/li&gt;
......
&lt;/ul&gt;
</code></pre>

<p>I want to add class <code>dark</code> and <code>light</code>, as per position of <code>li</code>.</p>

<ul>
<li>First <code>li</code> should be <code>light</code></li>
<li>2nd,3rd should be <code>dark</code></li>
<li>4th, 5th should be <code>light</code></li>
<li>same pattern....</li>
</ul>
