code: def as_xml(self):
          
          result = Stanza.as_xml(self)
          if self._subject:
              child = ElementTree.SubElement(result, self._subject_tag)
              child.text = self._subject
          if self._body:
              child = ElementTree.SubElement(result, self._body_tag)
              child.text = self._body
          if self._thread:
              child = ElementTree.SubElement(result, self._thread_tag)
              child.text = self._thread
          return result
docs: Return the XML stanza representation.
  
          Always return an independent copy of the stanza XML representation,
          which can be freely modified without affecting the stanza.
  
          :returntype: :etree:`ElementTree.Element`