title: Python lxml iterfind w/ namespace but prefix=None
body: <p>I want to perform <code>iterfind()</code> for elements which have a namespace but no prefix.  I'd like to call</p>
  
  <p><code>iterfind([tagname])</code> or <code>iterfind([tagname], [namespace dict])</code></p>
  
  <p>I don't care to enter the tag as follows every time: </p>
  
  <p><code>"{%s}tagname" %  tree.nsmap[None]</code></p>
  
  <p><strong>Details</strong></p>
  
  <p>I'm running through an xml response from a Google API.  The root node defines several namespaces, including one for which there is no prefix: <code>xmlns="http://www.w3.org/2005/Atom"</code></p>
  
  <p>It looks as though when I try to search through my etree, everything behaves as I would expect for elements with a prefix.  e.g.:</p>
  
  <pre><code>&gt;&gt;&gt; for x in root.iterfind('dxp:segment'): print x
  ...
  &lt;Element {http://schemas.google.com/analytics/2009}segment at 0x1211b98&gt;
  &lt;Element {http://schemas.google.com/analytics/2009}segment at 0x1211d78&gt;
  &lt;Element {http://schemas.google.com/analytics/2009}segment at 0x1211a08&gt;
  &gt;&gt;&gt;
  </code></pre>
  
  <p>But when I try to search for something without a prefix, the search doesn't automatically add the namespace for <code>root.nsmap[None]</code>.  e.g.:</p>
  
  <pre><code>&gt;&gt;&gt; for x in root.iterfind('entry'): print x
  ...
  &gt;&gt;&gt;
  </code></pre>
  
  <p>Even if I try to throw the namespace map in as the optional argument for <code>iterfind</code>, It won't attach the namespace.</p>