title: How to findall element with attribute with namespace which is not listed in the xml header
body: <p>my xml looks like this
  <a href="https://i.stack.imgur.com/y0RDS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/y0RDS.png" alt="source xml"></a></p>
  
  <p>I want to target all tags <code>&lt;langSet xml:lang="en"&gt;</code>. As you see, "xml" is not listed in "xmlns" attributes in the root. I'm using <code>xml.etree.ElementTree</code> to <code>parse</code> and <code>getroot</code> to initialize value of <code>root</code> below.</p>
  
  <p>So this call works just fine, but returns all languages:</p>
  
  <pre><code>root.findall('.//langSet')
  </code></pre>
  
  <p>And this call is what i need, but it returns empty list:</p>
  
  <pre><code>root.findall('.//langSet[@{xml}:lang="en"]')
  </code></pre>
  
  <p>Thank you for any help.</p>