title: xpath get element by index
body: <p>I have the below xpath expression</p>
  
  <pre><code>//div[@class="post-content"]//img
  </code></pre>
  
  <p>which runs on a html page, scanning for images.
  The above query returns a lot of images but I only want the second in the list.</p>
  
  <p>I have tried these with no luck:</p>
  
  <pre><code>//div[@class="post-content"]//img[1] and
  //div[@class="post-content"]//img[position()=1]
  </code></pre>