code: def test_validlist():
      response = client.get("/items/validlist")
      response.raise_for_status()
      assert response.json() == [
          {"name": "foo", "price": None, "owner_ids": None},
          {"name": "bar", "price": 1.0, "owner_ids": None},
          {"name": "baz", "price": 2.0, "owner_ids": [1, 2, 3]},
      ]
  
file_path: fastapi/tests/test_serialize_response.py
imports: from typing import List, Optional
  from fastapi import FastAPI
  from fastapi.testclient import TestClient
  from pydantic import BaseModel
label_desc: Use image node_id 6 for calling a global function with example usage: test_validlist() without return types