[xdoctest] reformat example code with google style in 271 (#56172)

* Update dlpack.py

* Apply suggestions from code review

* Apply suggestions from code review

python/paddle/utils/dlpack.py

@@ -39,13 +39,14 @@ def to_dlpack(x):
     Examples:
         .. code-block:: python
 
-            import paddle
-            # x is a tensor with shape [2, 4]
-            x = paddle.to_tensor([[0.2, 0.3, 0.5, 0.9],
-                                  [0.1, 0.2, 0.6, 0.7]])
-            dlpack = paddle.utils.dlpack.to_dlpack(x)
-            print(dlpack)
-            # <capsule object "dltensor" at 0x7f6103c681b0>
+            >>> import paddle
+            >>> # x is a tensor with shape [2, 4]
+            >>> x = paddle.to_tensor([[0.2, 0.3, 0.5, 0.9],
+            ...                       [0.1, 0.2, 0.6, 0.7]])
+            >>> dlpack = paddle.utils.dlpack.to_dlpack(x)
+            >>> print(dlpack)
+            >>> # doctest: +SKIP('the address will change in every run')
+            <capsule object "dltensor" at 0x7f6103c681b0>
     """
 
     if in_dygraph_mode():
@@ -76,16 +77,16 @@ def from_dlpack(dlpack):
     Examples:
         .. code-block:: python
 
-            import paddle
-            # x is a tensor with shape [2, 4]
-            x = paddle.to_tensor([[0.2, 0.3, 0.5, 0.9],
-                                  [0.1, 0.2, 0.6, 0.7]])
-            dlpack = paddle.utils.dlpack.to_dlpack(x)
-            x = paddle.utils.dlpack.from_dlpack(dlpack)
-            print(x)
-            # Tensor(shape=[2, 4], dtype=float32, place=CUDAPlace(0), stop_gradient=True,
-            #  [[0.20000000, 0.30000001, 0.50000000, 0.89999998],
-            #  [0.10000000, 0.20000000, 0.60000002, 0.69999999]])
+            >>> import paddle
+            >>> # x is a tensor with shape [2, 4]
+            >>> x = paddle.to_tensor([[0.2, 0.3, 0.5, 0.9],
+            ...                       [0.1, 0.2, 0.6, 0.7]])
+            >>> dlpack = paddle.utils.dlpack.to_dlpack(x)
+            >>> x = paddle.utils.dlpack.from_dlpack(dlpack)
+            >>> print(x)
+            Tensor(shape=[2, 4], dtype=float32, place=Place(cpu), stop_gradient=True,
+                   [[0.20000000, 0.30000001, 0.50000000, 0.89999998],
+                    [0.10000000, 0.20000000, 0.60000002, 0.69999999]])
     """
 
     t = type(dlpack)