code: def test_model_dump_json() -> None:
      class A(BaseModel):
          a: str
          b: int = 2
  
      assert (
          model_dump_json(A(a="aaa")).replace(" ", "")
          == '{"a":"aaa","b":2}'
      )
  
imports: from typing import Dict, List, Optional, Tuple, Union
  from pydantic import BaseModel, Field
  from typing_extensions import Annotated
  from autogen._pydantic import model_dump, model_dump_json, type2schema
label_desc: Use image node_id 3 for calling a global function with example usage: test_model_dump_json() without return types