IsModZero start from node other than 1

I need to add a class to node number 3 6 9.. and so on in a list

Example:

<p style="background-color:@page.IsModZero(3, "red","blue")"></p>

But this applies to node number 1,4,7...

How du i push the mod back or forward?


This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/49905-ismodzero-start-from-node-other-than-1