what is the cls meaning in mmengine runner.from_cfg(cls, cfg: ConfigType)

[vansin]

May you explain the meaning of the following cls, it is not very clear ?

mmengine/runner/runner.py#L422

    def from_cfg(cls, cfg: ConfigType) -> 'Runner':
        """Build a runner from config.

        Args:
            cfg (ConfigType): A config used for building runner. Keys of
                ``cfg`` can see :meth:`__init__`.

        Returns:
            Runner: A runner build from ``cfg``.
        """
        cfg = copy.deepcopy(cfg)
        runner = cls(
            model=cfg['model'],
            work_dir=cfg['work_dir'],
            train_dataloader=cfg.get('train_dataloader'),
            val_dataloader=cfg.get('val_dataloader'),
            test_dataloader=cfg.get('test_dataloader'),
            train_cfg=cfg.get('train_cfg'),
            val_cfg=cfg.get('val_cfg'),
            test_cfg=cfg.get('test_cfg'),
            auto_scale_lr=cfg.get('auto_scale_lr'),
            optim_wrapper=cfg.get('optim_wrapper'),
            param_scheduler=cfg.get('param_scheduler'),
            val_evaluator=cfg.get('val_evaluator'),
            test_evaluator=cfg.get('test_evaluator'),
            default_hooks=cfg.get('default_hooks'),
            custom_hooks=cfg.get('custom_hooks'),
            data_preprocessor=cfg.get('data_preprocessor'),
            load_from=cfg.get('load_from'),
            resume=cfg.get('resume', False),
            launcher=cfg.get('launcher', 'none'),
            env_cfg=cfg.get('env_cfg'),  # type: ignore
            log_processor=cfg.get('log_processor'),
            log_level=cfg.get('log_level', 'INFO'),
            visualizer=cfg.get('visualizer'),
            default_scope=cfg.get('default_scope', 'mmengine'),
            randomness=cfg.get('randomness', dict(seed=None)),
            experiment_name=cfg.get('experiment_name'),
            cfg=cfg,
        )

        return runner

[vansin]

当我使用 MMYOLO Debug 到这一步时，发现了 cls 就是 <class 'mmengine.runner.runner.Runner'> 这个类本身。
When I got to this point using MMYOLO Debug, I discovered that cls is the class <class 'mmengine.runner.runner'> itself.

然后去查找 python 的官方文档，发现 cls 是 classmethod 的一种固定用法，就是代表类本身，哈哈，暴露了 Python 基础不扎实。
Then I looked up the official python documentation and found that cls is a fixed use of classmethod, which stands for the class itself, haha, exposing a poor foundation in Python.

切换为Pycharm进行智能跳转的时候 cls 能够直接跳转到类，而vscode失败。
When switching to Pycharm for smart jumping cls can jump directly to the class, while vscode fails.

https://docs.python.org/3.8/library/functions.html?highlight=classmethod#classmethod