title: Getting values from xelement
body: <p>I'm learing linq. I have a Xelement like below </p>
  
  <pre><code>&lt;Customer&gt;
   &lt;Orders&gt;
     &lt;param id="13" title="Book1" /&gt;
     &lt;param id="15" title="Book2" /&gt;
   &lt;/Orders&gt;
  &lt;Customer/&gt;
  </code></pre>
  
  <p>How to get the value of id as a comma delimited string </p>