code: def restore_default(self, index):
          
          spec = self.get_configspec_str(index)
          if spec is None or isinstance(spec, Section):
              return
          try:
              default = self._vld.get_default_value(spec)
              defaultstr = self._val_to_str(default)
              self.setData(index, defaultstr)
          except KeyError:
              raise ConfigError("Missing Default Value in spec: \"%s\"" % spec)
docs: Set the value of the given index row to its default
  
          :param index:
          :type index:
          :returns:
          :rtype:
          :raises: