code: def download(self):
      return
  
file_path: graph4nlp/graph4nlp/pytorch/datasets/cnn.py
imports: import json
  import torch
  from nltk.tokenize import word_tokenize
  from graph4nlp.pytorch.data.dataset import Text2TextDataItem, Text2TextDataset
  from graph4nlp.pytorch.modules.utils.padding_utils import pad_2d_vals, pad_2d_vals_no_size
label_desc: Use image node_id 4 for calling the CNNDataset obj's underlying member method code with example usage: obj.download() without return types