code: def write_success_file():  # type: () -> None
      
      file_path = os.path.join(_env.output_dir, 'success')
      empty_content = ''
      write_file(file_path, empty_content)
docs: Create a file 'success' when training is successful. This file doesn't need to have any content.
      See: https://docs.aws.amazon.com/sagemaker/latest/dg/your-algorithms-training-algo.html