code: def tokenize(
      self, request: TokenizationRequest
  ) -> TokenizationRequestResult:
      # For reproducibility purposes, we use huggingface/gpt2 as the default tokenizer.
      # except for gpt-3.5 turbo models and gpt-4 that use the tiktoken library.
  
      if request.tokenizer != "openai/cl100k_base":
          raise ValueError(
              f"{request.tokenizer} is not supported."
              + "Only openai/cl100k-base is supported in HELM for now."
          )
  
      cache_key = asdict(request)
  
      try:
  
          def do_it():
              tokenizer = tiktoken.get_encoding(
                  self._get_tokenizer_name(request.tokenizer)
              )
              tokens = tokenizer.encode(request.text)
              if not request.encode:
                  tokens = [
                      tokenizer.decode([token]) for token in tokens
                  ]
              if request.truncation:
                  tokens = tokens[: request.max_length]
              return {"tokens": tokens}
  
          response, cached = self.cache.get(
              cache_key, wrap_request_time(do_it)
          )
  
          result = TokenizationRequestResult(
              success=True,
              cached=cached,
              text=request.text,
              tokens=[
                  TokenizationToken(value)
                  for value in response["tokens"]
              ],
              request_time=response["request_time"],
              error=None,
          )
          return result
      except Exception as error:
          raise ValueError(
              f"Error encoding with tiktoken: {error}."
              + "You might want to consider using huggingface/gpt2."
          )
  
file_path: H2O/h2o_hf/helm/src/helm/proxy/clients/openai_client.py
imports: from dataclasses import replace, asdict
  from typing import Any, Dict, List, Optional, cast
  import openai
  import tiktoken
  from helm.common.cache import Cache, CacheConfig
  from helm.common.request import Request, RequestResult, Sequence, Token
  from helm.common.tokenization_request import TokenizationRequest, TokenizationRequestResult, DecodeRequest, DecodeRequestResult, TokenizationToken
  from .client import Client, truncate_sequence, wrap_request_time
  from .chat_gpt_client import ChatGPTClient
label_desc: Use image node_id 5 for calling the OpenAIClient obj's underlying member method code with example usage: obj.tokenize(request) and returns: result, dict