docs: def update_xml_element(self):
          """
          Updates the xml element contents to matches the instance contents.
  
          :returns: Updated XML element
          :rtype: lxml.etree._Element
          """
  
          if not hasattr(self, 'xml_element'):
              self.xml_element = etree.Element(self.name, nsmap=NSMAP)
  
          self.xml_element.clear()
          self.xml_element.set('id', self.id)
  
          for child in self.children:
              child.update_xml_element()
              self.xml_element.append(child.xml_element)
  
          return self.xml_element