def _update_value_metric(
        self, value_inputs: Tuple[torch.Tensor, torch.Tensor]
    ) -> Optional[Dict[str, float]]:
        """
        Update metric in value input case

        Args:
            value_inputs: tuple of input tensor and target tensor

        Returns:
            result of metric update: None or metric values
        """
        return self._metric_update_method(*value_inputs)

        Update metric in value input case

        Args:
            value_inputs: tuple of input tensor and target tensor

        Returns:
            result of metric update: None or metric values
        
catalyst/callbacks/metric.py