title: Python XML parsing with ElementTree: findall retuns empty list
body: <p>My XML begins like this:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;?xml-stylesheet type="text/xsl" href="define2-0-0.xsl"?&gt;
  &lt;ODM
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns="http://www.cdisc.org/ns/odm/v1.3"
    xmlns:def="http://www.cdisc.org/ns/def/v2.0"
    xmlns:nciodm="http://ncicb.nci.nih.gov/xml/odm/EVS/CDISC"
    ODMVersion="1.3.2"
    FileType="Snapshot"
    FileOID="SDTM-Terminology-2015-06-26.odm.xml.."
    CreationDateTime="2016-08-30T16:37:21"&gt;
      &lt;Study OID="SDTM-Terminology-2015-06-26.odm.xml.."&gt;
      ...it goes on from there
  </code></pre>
  
  <p>I can parse it into am ELementTree object:</p>
  
  <pre><code>import xml.etree.ElementTree as ET
  root = tree.getroot()
  </code></pre>
  
  <p>This code:</p>
  
  <pre><code>for child in root:
      print "Child of root:  " + child.tag
  </code></pre>
  
  <p>Produces:</p>
  
  <pre><code>Child of root:  {&lt;some url&gt;}Study
  </code></pre>
  
  <p>I need to traverse several levels down the tree, and I don't want to have to use 7-8 nested "for child in..." loops.  I want to use XMLPath but I can't get anything to work.  This code:</p>
  
  <pre><code>for node in tree.findall('./Study')
      print(node.tag)
  </code></pre>
  
  <p>returns nothing.  I can't get it to return anything.  I've tried</p>
  
  <pre><code>for node in root.findall('./Study')
      print (node.tag)
  </code></pre>
  
  <p>and it also produces nothing.  I've tried all kinds of combinations of root &amp; tree, with and without the leading "./".  I can't get anything to work.  This is my first time working with ElementTree; can someone help me? </p>