class_docstr: A convenient vocab container that can store multiple BaseVocab instances, and support 
  safe serialization of all instances via state dicts. Each subclass of this base class 
  should implement the load_state_dict() function to specify how a saved state dict 
  should be loaded back.
code: def __init__(self, vocab_dict=None):
      self._vocabs = OrderedDict()
      if vocab_dict is None:
          return
      # check all values provided must be a subclass of the Vocab base class
      assert all(
          [isinstance(v, BaseVocab) for v in vocab_dict.values()]
      )
      for k, v in vocab_dict.items():
          self._vocabs[k] = v
  
imports: from copy import copy
  from collections import Counter, OrderedDict
  from collections.abc import Iterable
  import os
  import pickle
label_desc: Use image node_id 1 to create a new BaseMultiVocab object  with example: obj = BaseMultiVocab(vocab_dict)