title: extraction child text python with lxml
body: <p>i'm triying to extract from xml file (GPX) all informations related to the waypoints of my gpx file with lxml library.
  there is a subset of my gpx file.</p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;gpx
   version="1.0"
  creator="GPSBabel - http://www.gpsbabel.org"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns="http://www.topografix.com/GPX/1/0"
  xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd"&gt;
  &lt;time&gt;2006-01-23T02:00:28Z&lt;/time&gt;
  &lt;trk&gt;
    &lt;name&gt;08-JAN-06 02&lt;/name&gt;
  &lt;trkseg&gt;
  &lt;trkpt lat="-33.903422356" lon="151.175565720"&gt;
    &lt;ele&gt;19.844360&lt;/ele&gt;
  &lt;time&gt;2006-01-08T06:45:07Z&lt;/time&gt;
  &lt;/trkpt&gt;
  &lt;/trkseg&gt;
  &lt;/trk&gt;
  &lt;/gpx&gt;
  </code></pre>
  
  <p>i can get point latitude and longitude by:</p>
  
  <pre><code>node.get("lon") and node.get("lat")
  </code></pre>
  
  <p>but when i  try to get time with :</p>
  
  <pre><code>for element in root:
      if element.tag=="{http://www.topografix.com/GPX/1/0}time":
         time=str(element.text)
  </code></pre>
  
  <p>i get finally for example this kind of results</p>
  
  <pre><code>(1.45,32.12,'')
  </code></pre>
  
  <p>a blank value for time  how can i solve this </p>