title: lxml,Python. I can't get content of element: element.text is None
body: <p>I loaded a xml file from internet, and parsed with lxml. But I couldn't get the content by <code>'element'.text</code>. Both result and source are short, I will just write them.</p>
  
  <p>XML :</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;products&gt;
  &lt;product&gt;
  &lt;company&gt;&lt;![CDATA[google]]&gt;&lt;/company&gt;
  &lt;link&gt;&lt;![CDATA[http://www.google.com]]&gt;&lt;/link&gt;
  &lt;subject&gt;&lt;![CDATA[sushi]]&gt;&lt;/subject&gt;
  &lt;/product&gt;
  &lt;/products&gt;
  </code></pre>
  
  <p>Code :</p>
  
  <pre><code>import urllib2
  from lxml import etree
  from StringIO import StringIO
  
  rss = urllib2.urlopen("http://dizzy-v.co.kr/test/test.xml").read()
  tree = etree.parse(StringIO(rss), etree.HTMLParser())
  
  root = tree.getroot()
  for product in root.iter('product'):
      for element in product.iter():
          print element.text
  </code></pre>
  
  <p>result :</p>
  
  <pre><code>None
  None
  None
  </code></pre>