title: Get a node with a prespecified namespace
body: <p>How would I get the following etree node, where I don't have to qualify every operation with the namespace? For example:</p>
  
  <pre><code>&gt;&gt;&gt; c='''&lt;sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"&gt;
               &lt;sitemap&gt;&lt;loc&gt;http://www.vudu.com/sitemap-static.xml&lt;/loc&gt;&lt;/sitemap&gt;
           &lt;/sitemapindex&gt;'''
  &gt;&gt;&gt; node=etree.fromstring(c)
  &gt;&gt;&gt; node.xpath('//loc')
  []
  </code></pre>
  
  <p>How could I establish the <code>node</code> such that I can do <code>node.xpath(''/loc')</code> and get results?</p>