code: def save(self, data_folder: str):
      self.save_sentences(self._train, f"{data_folder}/train.txt")
      self.save_sentences(self._dev, f"{data_folder}/dev.txt")
      self.save_sentences(self._test, f"{data_folder}/test.txt")
  
file_path: underthesea/underthesea/corpus/categorized_corpus.py
imports: from pathlib import Path
  from typing import List, Union
  from underthesea.corpus import Corpus
  from underthesea.corpus.data import Sentence
label_desc: Use image node_id 6 for calling the CategorizedCorpus obj's underlying member method code with example usage: obj.save(data_folder) without return types