def METHOD_NAME(self) -> List[str]:
    """Called first time rule is evaluated to fetch & cache the ignore_words."""
    # Use str() in case bools are passed which might otherwise be read as bool
    ignore_words_config = str(getattr(self, "ignore_words"))
    if ignore_words_config and ignore_words_config != "None":
        self.ignore_words_list = self.split_comma_separated_string(
            ignore_words_config.lower()
        )
    else:
        self.ignore_words_list = []
    ignore_words_list = self.ignore_words_list
    return ignore_words_list