code: def __init__(self):
      self.itos = []
      self.stoi = {}
  
file_path: pytext/pytext/models/test/module_test.py
imports: import unittest
  from pytext.config.component import create_model
  from pytext.config.field_config import DictFeatConfig, FeatureConfig, WordFeatConfig
  from pytext.data import CommonMetadata
  from pytext.fields import FieldMeta
  from pytext.models.doc_model import DocModel
label_desc: Use image node_id 1 to create a new VocabStub object  with example: obj = VocabStub()