title: Return the XML source for the node with lxml
body: <p>Please imagine XML node in variable <code>n</code>.  </p>
  
  <p>If I access this node through MSXML, I can get node's XML source with <code>.xml</code> property, i.e. <code>n.xml</code> will return whole node source.</p>
  
  <p>How can I do the same with lxml?</p>