title: Parsing Node Value of XML in Python with ElementTree
body: <p>I have the following XML which I have parsed from a webpage:</p>
  
  <pre><code>&lt;!--
  Parts from the iGEM Registry of Standard Biological Parts
  --&gt;
  &lt;rsbpml&gt;
   &lt;part_list&gt;
    &lt;part&gt;
     &lt;part_id&gt;151&lt;/part_id&gt;
     &lt;part_name&gt;BBa_B0034&lt;/part_name&gt;
     &lt;part_short_name&gt;B0034&lt;/part_short_name&gt;
     &lt;part_short_desc&gt;RBS (Elowitz 1999) -- defines RBS efficiency&lt;/part_short_desc&gt;
     &lt;part_type&gt;RBS&lt;/part_type&gt;
     &lt;release_status&gt;Released HQ 2013&lt;/release_status&gt;
     &lt;sample_status&gt;In stock&lt;/sample_status&gt;
  </code></pre>
  
  <p>And I want to extract some of the values.</p>
  
  <p>For example I want to ouput the value <code>RBS</code> from <code>&lt;part_type&gt;</code>.</p>
  
  <p>I've tried the following:</p>
  
  <pre><code>bb_xml_raw = urllib2.urlopen("http://parts.igem.org/cgi/xml/part.cgi?part=BBa_B0034")
  self.parse = ET.parse(bb_xml_raw)
  self.root = self.parse.getroot()
  
  for part in self.root.findall('part_list'):
     print part.find('part_type').text
  </code></pre>
  
  <p>But it doesn't work, I get: AttributeError: <code>'NoneType' object has no attribute 'text'</code></p>
  
  <p>What am I doing wrong?</p>