langchain/callbacks/mlflow_callback.py/MlflowLogger/metrics
class MlflowLogger:    def metrics(
        self, data: Union[Dict[str, float], Dict[str, int]], step: Optional[int] = 0
    ) -> None:
        """To log all metrics in the input dict."""
        with self.mlflow.start_run(
            run_id=self.run.info.run_id, experiment_id=self.mlf_expid
        ):
            self.mlflow.log_metrics(data)