code: def complete_xml_element(self, xmlnode, doc):
          
          for field in self.fields:
              field.as_xml(xmlnode, doc)
docs: Complete the XML node with `self` content.
  
          :Parameters:
              - `xmlnode`: XML node with the element being built. It has already
                right name and namespace, but no attributes or content.
              - `doc`: document to which the element belongs.
          :Types:
              - `xmlnode`: `libxml2.xmlNode`
              - `doc`: `libxml2.xmlDoc`