code: def __str__(self):
      return "Total " + str(len(self.i2s)) + str(self.i2s[:10])
  
imports: import json
  import pickle
  import random
  import dgl
  import numpy
  import torch
label_desc: Use image node_id 3 for calling the Vocab obj's underlying member method code with example usage: obj.__str__() and returns: unknown