code: def update_metric(self, metric, labels, pre_sliced=False):
          
          for current_exec, (texec, islice) in enumerate(zip(self.train_execs, self.slices)):
              if not pre_sliced:
                  labels_slice = [label[islice] for label in labels]
              else:
                  labels_slice = labels[current_exec]
              metric.update(labels_slice, texec.outputs)
docs: Update evaluation metric with label and current outputs.