Update get_worker_info API (#29190)

* Update get_worker_info API

* Update dataloader_iter.py

* Update dataloader_iter.py

* Update dataloader_iter.py

python/paddle/fluid/dataloader/dataloader_iter.py

@@ -153,8 +153,8 @@ def get_worker_info():
         .. code-block:: python
 
             import math
+            import paddle
             import numpy as np
-            import paddle.fluid as fluid
             from paddle.io import IterableDataset, DataLoader, get_worker_info
 
             class SplitedIterableDataset(IterableDataset):
@@ -178,8 +178,7 @@ def get_worker_info():
                     for i in range(iter_start, iter_end):
                         yield np.array([i])
 
-            place = fluid.CPUPlace()
-            with fluid.dygraph.guard(place):
+            place = paddle.CPUPlace()
             dataset = SplitedIterableDataset(start=2, end=9)
             dataloader = DataLoader(
                 dataset,
@@ -188,7 +187,8 @@ def get_worker_info():
                 batch_size=1,
                 drop_last=True)
 
-                print(list(dataloader))
+            for data in dataloader:
+                print(data)
             # outputs: [2, 5, 3, 6, 4, 7]
 
     """