update docs

python/paddle/hapi/model.py

@@ -1031,6 +1031,7 @@ class Model(object):
                 a numpy array or paddle.Tensor, or a list of arrays or tensors 
                 (in case the model has multiple labels). If has no labels, 
                 set None. Default is None.
+            update (bool): Whether update parameters after loss.backward() computes. Using this to accumulate gradients. Default is True.
 
         Returns:
             A list of scalar training loss if the model has no metrics,
@@ -2046,9 +2047,6 @@ class Model(object):
 
                 outs = getattr(self, mode + '_batch')(*_inputs)
 
-                # outs = getattr(self, mode + '_batch')(data[:len(self._inputs)],
-                #                                       data[len(self._inputs):])
-
                 if self._metrics and self._loss:
                     metrics = [[l[0] for l in outs[0]]]
                 elif self._loss: