code: def test_positional_param() -> None:
      @required_args(["a"])
      def foo(a: str | None = None) -> str | None:
          return a
  
      assert foo("a") == "a"
      assert foo(None) is None
      assert foo(a="b") == "b"
  
      with pytest.raises(
          TypeError, match="Missing required argument: 'a'"
      ):
          foo()
  
file_path: openai-python/tests/test_required_args.py
imports: from __future__ import annotations
  import pytest
  from openai._utils import required_args
label_desc: Use image node_id 2 for calling a global function with example usage: test_positional_param() and returns: a