def _init_backbone(self, config) -> None:
        """
        Method to initialize the backbone. This method is called by the constructor of the base class after the
        pretrained model weights have been loaded.
        """
        self.config = config

        self.use_timm_backbone = getattr(config, "use_timm_backbone", False)
        self.backbone_type = BackboneType.TIMM if self.use_timm_backbone else BackboneType.TRANSFORMERS

        if self.backbone_type == BackboneType.TIMM:
            self._init_timm_backbone(config)
        elif self.backbone_type == BackboneType.TRANSFORMERS:
            self._init_transformers_backbone(config)
        else:
            raise ValueError(f"backbone_type {self.backbone_type} not supported.")

        Method to initialize the backbone. This method is called by the constructor of the base class after the
        pretrained model weights have been loaded.
        
dpkd/transformers/src/transformers/utils/backbone_utils.py