class_docstr: Vocabulary base class.
  
  :ivar name: Name of the vocabulary.
  :ivar general_tokens: General tokens.
  :ivar background_tokens: Background tokens.
docstr: Returns the number of tokens
docstr_tok: ["Returns","the","number","of","tokens"]
code: def size(self) -> int:
      """Returns the number of tokens"""
      return len(self.token2index)
  
imports: from dataclasses import dataclass, field
  from functools import cached_property
  from typing import TYPE_CHECKING, Dict, List, Tuple, Union, cast
  import dask
  import pandas
  from .decorators import save_pickle, save_tsv
  from .serialize import DATA_ROOT
  from .sources.base import TokenSource
label_desc: Use image node_id 6 for calling the Vocabulary obj's underlying member method code with example usage: obj.size() and returns: len