modify Sequential doc, test=develop (#27608)

python/paddle/fluid/dygraph/container.py

@@ -34,27 +34,26 @@ class Sequential(Layer):
     Examples:
         .. code-block:: python
 
-            import paddle.fluid as fluid
+            import paddle
             import numpy as np
 
             data = np.random.uniform(-1, 1, [30, 10]).astype('float32')
-            with fluid.dygraph.guard():
-                data = fluid.dygraph.to_variable(data)
-                # create Sequential with iterable Layers
-                model1 = fluid.dygraph.Sequential(
-                    fluid.Linear(10, 1), fluid.Linear(1, 2)
-                )
-                model1[0]  # access the first layer
-                res1 = model1(data)  # sequential execution
-
-                # create Sequential with name Layer pairs
-                model2 = fluid.dygraph.Sequential(
-                    ('l1', fluid.Linear(10, 2)),
-                    ('l2', fluid.Linear(2, 3))
-                )
-                model2['l1']  # access l1 layer
-                model2.add_sublayer('l3', fluid.Linear(3, 3))  # add sublayer
-                res2 = model2(data)  # sequential execution
+            data = paddle.to_tensor(data)
+            # create Sequential with iterable Layers
+            model1 = paddle.nn.Sequential(
+                paddle.nn.Linear(10, 1), paddle.nn.Linear(1, 2)
+            )
+            model1[0]  # access the first layer
+            res1 = model1(data)  # sequential execution
+
+            # create Sequential with name Layer pairs
+            model2 = paddle.nn.Sequential(
+                ('l1', paddle.nn.Linear(10, 2)),
+                ('l2', paddle.nn.Linear(2, 3))
+            )
+            model2['l1']  # access l1 layer
+            model2.add_sublayer('l3', paddle.nn.Linear(3, 3))  # add sublayer
+            res2 = model2(data)  # sequential execution
 
     """