code: def update_metric(self, eval_metric, labels, pre_sliced=False):
          
          assert self.binded and self.params_initialized
          self._curr_module.update_metric(eval_metric, labels, pre_sliced)
docs: Evaluates and accumulates evaluation metric on outputs of the last forward computation.
  
          Parameters
          ----------
          eval_metric : EvalMetric
          labels : list of NDArray
              Typically ``data_batch.label``.