code: def test_convert_positional_args_mypy_type_inference() -> None:
      previous_positional_arg_names: List[str] = []
      decorator_converter = convert_positional_args(
          previous_positional_arg_names=previous_positional_arg_names
      )
      assert callable(decorator_converter)
  
      class _Sample:
          def __init__(self) -> None:
              pass
  
          def method(self) -> bool:
              return True
  
      def _func_sample() -> _Sample:
          return _Sample()
  
      def _func_none() -> None:
          pass
  
      ret_none = decorator_converter(_func_none)()
      assert ret_none is None
  
      ret_sample = decorator_converter(_func_sample)()
      assert isinstance(ret_sample, _Sample)
      assert ret_sample.method()
  
file_path: optuna/tests/test_convert_positional_args.py
imports: import re
  from typing import List
  import pytest
  from optuna._convert_positional_args import convert_positional_args
label_desc: Use image node_id 5 for calling a global function with example usage: test_convert_positional_args_mypy_type_inference() and returns: _Sample, True