  text_column(str): name of column containing the text
        label_column(list): list of columns that are to be treated as labels
        val_filepath(string): file path to test CSV.  If not supplied,
                               10% of documents in training CSV will be
                               used for testing/validation.
        max_features(int): max num of words to consider in vocabulary
                           Note: This is only used for preprocess_mode=&#39;standard&#39;.
        maxlen(i