code: def override_special_tokens(self, opt):
      # now override
      self.start_token = self.hf_tokenizer.pad_token
      self.end_token = self.hf_tokenizer.eos_token
      self.null_token = self.hf_tokenizer.pad_token
      self.unk_token = self.hf_tokenizer.unk_token
  
      self._unk_token_idx = self.hf_tokenizer.unk_token_id
  
      self.start_idx = self[self.start_token]
      self.end_idx = self[self.end_token]
      self.null_idx = self[self.null_token]
  
imports: import os
  import re
  from abc import ABC, abstractmethod, abstractproperty
  from collections import defaultdict
  from typing import List
  from parlai.core.dict import DictionaryAgent
  from parlai.core.opt import Opt
  from parlai.utils.io import PathManager
label_desc: Use image node_id 4 for calling the T5DictionaryAgent obj's underlying member method code with example usage: obj.override_special_tokens(opt) without return types