diff --git a/python/paddle/fluid/layers/tensor.py b/python/paddle/fluid/layers/tensor.py
index 1cbef96a174c4a17ffed8fb5d901cdb167c9a402..4be0dc6a6bfeed3ac254f5c363d3560973c031b4 100644
--- a/python/paddle/fluid/layers/tensor.py
+++ b/python/paddle/fluid/layers/tensor.py
@@ -193,9 +193,7 @@ def assign(input, output):
     helper = LayerHelper('assign', **locals())
     if isinstance(input, Variable):
         helper.append_op(
-            type='assign',
-            inputs={'X': [input]},
-            outputs={'Out': [output]})
+            type='assign', inputs={'X': [input]}, outputs={'Out': [output]})
     elif isinstance(input, numpy.ndarray):
         dtype = convert_np_dtype_to_dtype_(input.dtype)
         if dtype == VarDesc.VarType.FP32: