code: def test_http_client_option() -> None:
      assert openai.http_client is None
  
      original_http_client = openai.completions._client._client
      assert original_http_client is not None
  
      new_client = httpx.Client()
      openai.http_client = new_client
  
      assert openai.completions._client._client is new_client
  
imports: from __future__ import annotations
  import os
  import httpx
  import pytest
  from httpx import URL
  import openai
  from openai import DEFAULT_TIMEOUT, DEFAULT_MAX_RETRIES
  import contextlib
  from typing import Iterator
  from openai.lib.azure import AzureOpenAI
label_desc: Use image node_id 8 for calling a global function with example usage: test_http_client_option() without return types