class_docstr: A mapping from indices to vocab elements.
class_docstr_tok: ["A","mapping","from","indices","to","vocab","elements","."]
code: def __len__(self):
      return len(self._vocab)
  
imports: import itertools
  from collections import Counter
  from typing import Dict, List, Optional, Tuple
  import torch
  from pytext.common.constants import SpecialTokens, Token
  from pytext.utils import cuda, precision
label_desc: Use image node_id 11 for calling the Vocabulary obj's underlying member method code with example usage: obj.__len__() and returns: len