add global batch normalization

mindspore/nn/layer/normalization.py

@@ -111,8 +111,8 @@ class _BatchNorm(Cell):
 
     def list_group(self, world_rank, group_size):
         if group_size > get_local_rank_size():
-            raise ValueError("group size can not be greater than local rank size, group size is {}, local_rank_size is {}".format(
-                group_size, get_local_rank_size()))
+            raise ValueError("group size can not be greater than local rank size, group size is {}, "
+                             "local_rank_size is {}".format(group_size, get_local_rank_size()))
         if len(world_rank) % group_size != 0:
             raise ValueError("please make your group size correct.")
         world_rank_list = zip(*(iter(world_rank),) *group_size)