title: xpath to exclude elements that have a class
body: <p>I'm trying to select all dom elements that have <code>id="mydiv"</code> but exclude the ones that also have the <code>class="exclass"</code>. Right now I'm doing the first part <code>//*[@id="mydiv"]</code>. How do I add the class exclusion part?</p>
  
  <p>P.S. In case you're wondering why I need to select multiple elements that have the same id, I'm just working on an existing DOM that I can't control. </p>