code: def idx2word(self, n_w):
      return self.word_list[n_w]
  
imports: import os
  import re
  from collections import Counter
  from itertools import chain
  import torch
  from mmf.common.registry import registry
  from mmf.utils.file_io import PathManager
  from mmf.utils.general import get_absolute_path
label_desc: Use image node_id 3 for calling the VocabDict obj's underlying member method code with example usage: obj.idx2word(n_w) and returns: self