def hook_type(self) -> str:
        """Hook type Subclasses should overwrite this function to return a
        string value in.

        {`forward`, `forward_pre`, `backward`}
        """
Hook type Subclasses should overwrite this function to return a
        string value in.

        {`forward`, `forward_pre`, `backward`}
        
mmpose/mmpose/models/utils/regularizations.py