title: Adding extended data to placemarks in python with pykml
body: <p>I have uploaded some addresses to batchgeo along with several columns of data. I've downloaded the kml file which then has the coordiantes. The data structure is the following:</p>
  
  <pre><code>&lt;?xml version="1.0" ?&gt;
  &lt;kml xmlns="http://earth.google.com/kml/2.0"&gt;
      &lt;Document&gt;
          &lt;Placemark&gt;
              &lt;name&gt;...&lt;/name&gt;
              &lt;description&gt;....&lt;/description&gt;
              &lt;Point&gt;
                  &lt;coordinates&gt;-3.1034345755337,57.144817425039,0&lt;/coordinates&gt;
              &lt;/Point&gt;&lt;address&gt;...&lt;/address&gt;
              &lt;styleUrl&gt;#0&lt;/styleUrl&gt;
          &lt;/Placemark&gt;
      &lt;/Document&gt;
  &lt;/kml&gt;
  </code></pre>
  
  <p>The "description" tag is a jumbled mess which has the extended data when you click on a point in Google Maps/Earth (url, address etc.). I now want to add some details underneath the current extended data. My current tack is to use <a href="http://packages.python.org/pykml/tutorial.html#building-pykml-python-scripts" rel="nofollow">pykml</a>, but I can't find an extended data attribute of a pykml object, and I don't see it listed in the documentation. When I click on a placemark in Google earth I want this to appear:</p>
  
  <pre><code>&lt;Description&gt;
  item 1
  item 2
  item 3
  &lt;/Description&gt;
  New data
  </code></pre>
  
  <p>Could you suggest how to achieve this? Thanks. (btw, <a href="http://code.google.com/p/pylibkml/wiki/BasicTutorial" rel="nofollow">pylibkml</a> has this feature but it has been discontinued and I can't find a download link!)</p>