code: def SetDefault(self, name, value):
      
      fl = self.FlagDict()
      if name not in fl:
        self._SetUnknownFlag(name, value)
        return
      if self.IsParsed():
        logging.warn(
            'FLAGS.SetDefault called on flag "%s" after flag parsing. Call this '
            'method at the top level of a module to avoid overwriting the value '
            'passed at the command line.',
            name)
      fl[name]._set_default(value)  # pylint: disable=protected-access
      self._AssertValidators(fl[name].validators)
docs: Changes the default value (and current value) of the named flag object.
  
      Call this method at the top level of a module to avoid overwriting the value
      passed at the command line.
  
      Args:
        name: A string, the name of the flag to modify.
        value: The new default value.
  
      Raises:
        UnrecognizedFlagError: When there is no registered flag named name.
        IllegalFlagValueError: When value is not valid.