code: def get_idx_symbol(self, idx):
      if idx not in self.idx2symbol:
          return self.unk_token
      return self.idx2symbol[idx]
  
imports: from operator import itemgetter
  import numpy
label_desc: Use image node_id 4 for calling the Vocab obj's underlying member method code with example usage: obj.get_idx_symbol(idx) and returns: self, self