def compute_key_value(self) -> Dict[str, torch.Tensor]:
        """
        Get metric average over all examples

        Returns:
            Dict with one element-custom metric
        """
        mean, std = self.compute()
        return {
            self.metric_name: mean,
            f"{self.metric_name}/mean": mean,
            f"{self.metric_name}/std": std,
        }

        Get metric average over all examples

        Returns:
            Dict with one element-custom metric
        
catalyst/metrics/_functional_metric.py