code: def test_base_url_option() -> None:
      assert openai.base_url is None
      assert openai.completions._client.base_url == URL(
          "https://api.openai.com/v1/"
      )
  
      openai.base_url = "http://foo.com"
  
      assert openai.base_url == URL("http://foo.com")
      assert openai.completions._client.base_url == URL(
          "http://foo.com"
      )
  
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 3 for calling a global function with example usage: test_base_url_option() without return types