code: def to_XML(self, xml_declaration=True, xmlns=True):
          
          root_node = self._to_DOM()
          if xmlns:
              xmlutils.annotate_with_XMLNS(root_node,
                                           NO2INDEX_XMLNS_PREFIX,
                                           NO2INDEX_XMLNS_URL)
          return xmlutils.DOM_node_to_XML(root_node, xml_declaration)
docs: Dumps object fields to an XML-formatted string. The 'xml_declaration'
          switch  enables printing of a leading standard XML line containing XML
          version and encoding. The 'xmlns' switch enables printing of qualified
          XMLNS prefixes.
  
          :param XML_declaration: if ``True`` (default) prints a leading XML
              declaration line
          :type XML_declaration: bool
          :param xmlns: if ``True`` (default) prints full XMLNS prefixes
          :type xmlns: bool
          :returns: an XML-formatted string