code: def add(self, word):
      if word not in self:
          wid = self.word2id[word] = len(self)
          self.id2word[wid] = word
          return wid
      else:
          return self[word]
  
imports: import argparse
  from collections import Counter
  from itertools import chain
  import torch
  from util import read_corpus
label_desc: Use image node_id 8 for calling the VocabEntry obj's underlying member method code with example usage: obj.add(word) and returns: wid, self