def compute_key_value(self) -> Dict[str, float]:
        """Computes the metric based on it's accumulated state.

        By default, this is called at the end of each loader
        (`on_loader_end` event).

        Returns:
            Dict: computed value in key-value format.  # noqa: DAR202
        """
        # @TODO: could be refactored - we need custom exception here
        # we need this method only for callback metric logging
        pass
Computes the metric based on it's accumulated state.

        By default, this is called at the end of each loader
        (`on_loader_end` event).

        Returns:
            Dict: computed value in key-value format.  # noqa: DAR202
        
catalyst/metrics/_metric.py