fix tracedLayer sample code

Author: Aurelius84

python/paddle/fluid/compiler.py

@@ -691,16 +691,12 @@ def patch_program_cache(ipu_strategy):
         Returns:
             None
         """
-        from paddle.jit.dy2static.program_translator import (
-            ProgramCache,
-        )
         from paddle.jit.dy2static.program_translator import (
             CacheKey,
-        )
-        from ..fluid.dygraph.dygraph_to_static import logging_utils
-        from paddle.jit.dy2static.program_translator import (
+            ProgramCache,
             MAX_TRACED_PROGRAM_COUNT,
         )
+        from ..fluid.dygraph.dygraph_to_static import logging_utils
         from ..fluid.dygraph.dygraph_to_static.partial_program import (
             partial_program_from,
         )

python/paddle/jit/api.py

@@ -1568,6 +1568,8 @@ def trace(layer, inputs):
         Examples:
             .. code-block:: python:
 
+                import os
+                os.environ['FLAGS_enable_eager_mode'] = '0'
                 import paddle
 
                 class ExampleLayer(paddle.nn.Layer):
@@ -1618,6 +1620,8 @@ def set_strategy(self, build_strategy=None, exec_strategy=None):
         Examples:
             .. code-block:: python:
 
+                import os
+                os.environ['FLAGS_enable_eager_mode'] = '0'
                 import paddle
 
                 class ExampleLayer(paddle.nn.Layer):
@@ -1722,6 +1726,8 @@ def save_inference_model(self, path, feed=None, fetch=None, **kwargs):
         Examples:
             .. code-block:: python:
 
+                import os
+                os.environ['FLAGS_enable_eager_mode'] = '0'
                 import numpy as np
                 import paddle