ting/validation.
        max_features(int): max num of words to consider in vocabulary.
                           Note: This is only used for preprocess_mode=&#39;standard&#39;.
        maxlen(int): each document can be of most &lt;maxlen&gt; words. 0 is used as padding ID.
        ngram_range(int): size of multi-word phrases to consider
                          e.g., 2 will consider both 1-word phrases and 2-word phrases
                               limited by max_features
        val_pct(float): Propo