code: def override_special_tokens(self, opt):
      # define special tokens
      self._define_special_tokens(opt)
      # now override
      self.start_idx = self.hf_tokenizer.convert_tokens_to_ids(
          [self.start_token]
      )[0]
      self.end_idx = self.hf_tokenizer.convert_tokens_to_ids(
          [self.end_token]
      )[0]
      self.null_idx = self.hf_tokenizer.convert_tokens_to_ids(
          [self.null_token]
      )[0]
      self.unk_idx = self.hf_tokenizer.convert_tokens_to_ids(
          [self.unk_token]
      )[0]
      # set tok2ind for special tokens
      self.tok2ind[self.end_token] = self.end_idx
      self.tok2ind[self.start_token] = self.start_idx
      self.tok2ind[self.null_token] = self.null_idx
      self.tok2ind[self.unk_token] = self.unk_idx
      # set ind2tok for special tokens
      self.ind2tok[self.end_idx] = self.end_token
      self.ind2tok[self.start_idx] = self.start_token
      self.ind2tok[self.null_idx] = self.null_token
      self.ind2tok[self.unk_idx] = self.unk_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 6 for calling the Gpt2DictionaryAgent obj's underlying member method code with example usage: obj.override_special_tokens(opt) without return types