rtion of training to use for validation.
                        Has no effect if val_filepath is supplied.
        preprocess_mode (str):  Either &#39;standard&#39; (normal tokenization) or one of {&#39;bert&#39;, &#39;distilbert&#39;}
                                tokenization and preprocessing for use with
                                BERT/DistilBert text classification model.
        lang (str):            language.  Auto-detected if None.
        is_regression(bool):  If True, integer targets will