def _resolve_callbacks(
        self,
        model: Task,
        strategy: Union[str, BaseFinetuning, Tuple[str, int], Tuple[str, Tuple[int, int]]] = "no_freeze",
        train_bn: bool = True,
    ):
        """This function is used to select the `BaseFinetuning` to be used for finetuning."""
        if isinstance(strategy, str) and strategy == "no_freeze":
            warnings.warn("The model contains a default finetune callback.", UserWarning)
        finetuning_callback = model.configure_finetune_callback(strategy=strategy, train_bn=train_bn)
        if len(finetuning_callback) > 1:
            raise ValueError("Create a list with only 1 finetuning callback.")
        self.callbacks = self._merge_callbacks(self.callbacks, finetuning_callback)
This function is used to select the `BaseFinetuning` to be used for finetuning.
src/flash/core/trainer.py