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.
docstr: Build a state dict by iteratively calling state_dict() of all vocabs. 
docstr_tok: ["Build","a","state","dict","by","iteratively","calling","state_dict","(",")","of","all","vocabs","."]
code: def state_dict(self):
      """Build a state dict by iteratively calling state_dict() of all vocabs."""
      state = OrderedDict()
      for k, v in self._vocabs.items():
          state[k] = v.state_dict()
      return state
  
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 7 for calling the BaseMultiVocab obj's underlying member method code with example usage: obj.state_dict() and returns: state