code: def set_value(self, format, *args):
          
          return lib.zconfig_set_value(self._as_parameter_, format, *args)
docs: Set new value for config item. The new value may be a string, a printf
  format, or NULL. Note that if string may possibly contain '%', or if it
  comes from an insecure source, you must use '%s' as the format, followed
  by the string.