code: def __init__(self, data_file: str):
      super().__init__(data_file=data_file)
      self.tokenizer = CharacterTokenizer()
  
      df = pd.read_csv(data_file)
      data_vocab = Vocabulary(unk_token="@")
      target_vocab = Vocabulary(add_unk=False)
  
      # Add surnames and nationalities to vocabulary
      for index, row in df.iterrows():
          surname = row.surname
          nationality = row.nationality
          data_vocab.add_many(
              tokens=self.tokenizer.tokenize(text=surname)
          )
          target_vocab.add_token(token=nationality)
  
      self.data_vocab = data_vocab
      self.target_vocab = target_vocab
  
imports: import numpy
  import pandas
  import torch
  from transfer_nlp.common.tokenizers import CharacterTokenizer
  from transfer_nlp.loaders.loaders import DatasetSplits, DataFrameDataset
  from transfer_nlp.loaders.vectorizers import Vectorizer
  from transfer_nlp.loaders.vocabulary import Vocabulary
  from transfer_nlp.plugins.config import register_plugin
  from transfer_nlp.plugins.helpers import ObjectHyperParams
label_desc: Use image node_id 1 to create a new TestVectorizer object from inherited base classes: Vectorizer with example: obj = TestVectorizer(data_file)