def on_epoch_end(self, runner: "IRunner") -> None:
        """
        Epoch end hook: the callback delete the model.

        Args:
            runner: current runner
        """
        # We need this for the control of a loader order.
        self.model = None

        Epoch end hook: the callback delete the model.

        Args:
            runner: current runner
        
catalyst/callbacks/sklearn_model.py