title: Python ElementTree parsing unbound prefix error
body: <p>I am learning ElementTree in python. Everything seems fine except when I try to parse the xml file with prefix:</p>
  
  <p><code>test.xml</code>:</p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;abc:data&gt;
     &lt;abc:country name="Liechtenstein" rank="1" year="2008"&gt;
     &lt;/abc:country&gt;
     &lt;abc:country name="Singapore" rank="4" year="2011"&gt;
     &lt;/abc:country&gt;
     &lt;abc:country name="Panama" rank="5" year="2011"&gt;
     &lt;/abc:country&gt;
  &lt;/abc:data&gt;
  </code></pre>
  
  <p>When I try to parse the xml:</p>
  
  <pre><code>import xml.etree.ElementTree as ET
  tree = ET.parse('test.xml')
  </code></pre>
  
  <p>I got the following error:</p>
  
  <pre><code>xml.etree.ElementTree.ParseError: unbound prefix: line 2, column 0
  </code></pre>
  
  <p>Do I need to specify something in order to parse a xml file with prefix?</p>