al and  y_val is supplied.
    preprocess_mode (str):  Either 'standard' (normal tokenization) or one of {'bert', 'distilbert'}
                            tokenization and preprocessing for use with
                            BERT/DistilBert text classification model.
    lang (str):            language.  Auto-detected if None.
    random_state(int):      If integer is supplied, train/test split is reproducible.
                            If None, train/test split will be random.
    verbose (boolean): v