code: def _setter(self):
          
          def set_attr_value(obj, value):
              if value is None or value == self._default:
                  if self._clark_name in obj.attrib:
                      del obj.attrib[self._clark_name]
                  return
              str_value = self._simple_type.to_xml(value)
              obj.set(self._clark_name, str_value)
          return set_attr_value
docs: Return a function object suitable for the "set" side of the attribute
          property descriptor.