code: def _build_vocab(self):
      self.vocab = utils.Vocab(self.cfg.vocab_size)
      vp = self.cfg.vocab_path_train
      self.vocab.load_vocab(vp)
      return self.vocab.vocab_size
  
file_path: TextBox/textbox/evaluator/utils/multiwoz/reader.py
imports: import logging
  import json
  import spacy
  from collections import OrderedDict
  from .None import utils
  from .None import ontology
  from .db_ops import MultiWozDB
label_desc: Use image node_id 2 for calling the MultiWozReader obj's underlying member method code with example usage: obj._build_vocab() and returns: self