docstr: At least 2 reserved keys should be fiiled: 'vocab' and 'data'.
docstr_tok: ["At","least","2","reserved","keys","should","be","fiiled",":","'vocab","'","and","'data","'","."]
code: def processed_file_names(self):
      """At least 2 reserved keys should be fiiled: 'vocab' and 'data'."""
      return {"vocab": "vocab.pt", "data": "data.pt"}
  
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 3 for calling the CNNDataset obj's underlying member method code with example usage: obj.processed_file_names() and returns: dict