title: Traversing TEI in Python 3, text comes up empty for some entities
body: <p>I have a TEI-encoded xml file with entities as follows:</p>
  
  <pre><code>&lt;sp&gt;
      &lt;speaker rend="italic"&gt;Sampson.&lt;/speaker&gt;
      &lt;ab&gt;
           &lt;lb n="5"/&gt;
           &lt;hi rend="italic"&gt;Gregory:&lt;/hi&gt;
           &lt;seg type="homograph"&gt;A&lt;/seg&gt; my word wee'l not carry coales.&lt;lb n="6"/&gt;
      &lt;/ab&gt;
  &lt;/sp&gt;
  &lt;sp&gt;
       &lt;speaker rend="italic"&gt;Greg.&lt;/speaker&gt;
       &lt;ab&gt;No, for then we should be Colliars.
           &lt;lb n="7" rend="rj"/&gt;
       &lt;/ab&gt;
  &lt;/sp&gt;
  </code></pre>
  
  <p>The full file is very large but can be accessed here: <a href="http://ota.ox.ac.uk/desc/5721" rel="nofollow">http://ota.ox.ac.uk/desc/5721</a>. I'm attempting to use Python 3 to traverse the xml and get all the text associated with the  tag, which is where the dialogue is found. </p>
  
  <pre><code>import xml.etree.ElementTree as etree
  tree = etree.parse('romeo_juliet_5721.xml')
  doc = tree.getroot()
  for i in doc.iter(tag='{http://www.tei-c.org/ns/1.0}ab'):   
          print(i.tag, i.text)
  &gt;&gt;&gt; http://www.tei-c.org/ns/1.0}ab 
  &gt;&gt;&gt;                  
  &gt;&gt;&gt; {http://www.tei-c.org/ns/1.0}ab No, for then we should be Colliars.
  </code></pre>
  
  <p>The output catches the  entities just fine but doesn't recognize "my word wee'l not carry coales" as the text of the first ab. If it's within a different element, I'm not seeing it. I've thought about converting the entire element to a string and getting the element text using regex (or by stripping all xml tags), but I would rather understand what's happening here. Thanks for any help you can provide.</p>