Update metric.py

python/mxnet/metric.py

diff --git a/python/mxnet/metric.py b/python/mxnet/metric.py
index c427fc2..2870fab 100644
--- a/python/mxnet/metric.py
+++ b/python/mxnet/metric.py
@@ -263,7 +263,7 @@
             num += pred.size
         self.sum_metric += loss
         self.num_inst += num
-        
+
     def get(self):
         return (self.name, math.exp(self.sum_metric/self.num_inst))