fix code style

Author: Aurelius84

python/paddle/fluid/tests/unittests/test_set_value_op.py

@@ -110,13 +110,13 @@ class TestSetValueItemSliceInWhile(TestSetValueApi):
     def _call_setitem(self, x):
         def cond(i, x):
             return i < 1
-        
+
         def body(i, x):
             x[i] = self.value
-            i = i+1
+            i = i + 1
             return i, x
-        
-        i = paddle.zeros(shape=(1,), dtype='int32')
+
+        i = paddle.zeros(shape=(1, ), dtype='int32')
         i, x = paddle.fluid.layers.while_loop(cond, body, [i, x])
 
     def _get_answer(self):