code: def _strip_undefok_args(undefok, args):
    
    if undefok:
      undefok_names = set(name.strip() for name in undefok.split(','))
      undefok_names |= set('no' + name for name in undefok_names)
      # Remove undefok flags.
      args = [arg for arg in args if not _is_undefok(arg, undefok_names)]
    return args
docs: Returns a new list of args after removing flags in --undefok.