class_docstr: Abstract BPE Helper.
  
  BPE Helper subclasses must implement appropriate abstractmethods.
class_docstr_tok: ["Abstract","BPE","Helper",".","BPE","Helper","subclasses","must","implement","appropriate","abstractmethods","."]
code: def add_cmdline_args(
      cls, parser: ParlaiParser, partial_opt: Optional[Opt] = None
  ) -> ParlaiParser:
      parser = parser.add_argument_group("BPEHelper Arguments")
      parser.add_argument(
          "--bpe-vocab",
          type=str,
          help="path to pre-trained tokenizer vocab",
      )
      parser.add_argument(
          "--bpe-merge",
          type=str,
          help="path to pre-trained tokenizer merge",
      )
      parser.add_argument(
          "--bpe-add-prefix-space",
          type="bool",
          hidden=True,
          help="add prefix space before encoding",
      )
      parser.add_argument(
          "--bpe-dropout",
          type=float,
          default=None,
          help="Use BPE dropout during training.",
      )
      return parser
  
imports: from parlai.core.params import ParlaiParser
  from abc import ABC, abstractmethod
  from functools import lru_cache
  import json
  import os
  import random
  import re
  from typing import Dict, List, Optional, Set, Tuple
  from typing_extensions import final
  from parlai.core.build_data import download, make_dir
  from parlai.core.opt import Opt
  from parlai.utils.misc import warn_once
  from parlai.utils.typing import TShared
  from parlai.utils.io import PathManager
  import parlai.utils.logging
label_desc: Use image node_id 2 for calling the BPEHelper obj's underlying member method code with example usage: obj.add_cmdline_args(cls, parser, partial_opt) and returns: parser