diff --git a/python/paddle/fluid/layers/io.py b/python/paddle/fluid/layers/io.py
index d56fa76300e7054ef71a7729483a579fa35f1dac..27c9cc3280b332cd9aeb0169a1ec0c06b2a8647e 100644
--- a/python/paddle/fluid/layers/io.py
+++ b/python/paddle/fluid/layers/io.py
@@ -842,6 +842,13 @@ def __create_unshared_decorated_reader__(op_type, reader, attrs, name=None):
 def shuffle(reader, buffer_size):
     """
     Shuffle the reader.
+
+    Args:
+        reader(Variable): The reader to be decorated with 'shuffling'.
+        buffer_size(int): The pre-read number of data in :code:`reader`.
+
+    Returns:
+        Variable: The reader which has been decorated with 'shuffling'.
     """
     return __create_unshared_decorated_reader__(
         'create_shuffle_reader', reader, {'buffer_size': int(buffer_size)})
diff --git a/python/paddle/fluid/layers/nn.py b/python/paddle/fluid/layers/nn.py
index 8c0ef7a82421ffc04bf669e6850e075226c09d27..dccd57e438133fac5e4ab7da335fb31a7bb68ea9 100644
--- a/python/paddle/fluid/layers/nn.py
+++ b/python/paddle/fluid/layers/nn.py
@@ -6367,7 +6367,7 @@ def stack(x, axis=0):
     if not isinstance(x, list) and not isinstance(x, tuple):
         x = [x]
 
-    out = helper.create_tmp_variable(x[0].dtype)
+    out = helper.create_tmp_variable(dtype=x[0].dtype)
     helper.append_op(
         type='stack', inputs={'X': x}, outputs={'Y': out},
         attrs={'axis': axis})
@@ -6404,8 +6404,8 @@ def unstack(x, axis=0, num=None):
             num = x.shape[axis]
 
     outs = []
-    for _ in num:
-        outs.append(helper.create_tmp_variable(x.dtype))
+    for _ in xrange(num):
+        outs.append(helper.create_tmp_variable(dtype=x.dtype))
 
     helper.append_op(
         type='unstack',