Fix API example code of save_inference_model (#17274)

* Fix API example code of save_inference_model

test=develop

* Add "import" in exmaple of save_inference_model

* Fix typo "exsample" -> "example"

test=develop

paddle/fluid/API.spec

@@ -52,8 +52,8 @@ paddle.fluid.io.save_persistables (ArgSpec(args=['executor', 'dirname', 'main_pr
 paddle.fluid.io.load_vars (ArgSpec(args=['executor', 'dirname', 'main_program', 'vars', 'predicate', 'filename'], varargs=None, keywords=None, defaults=(None, None, None, None)), ('document', '0a5308f496632ab1ec3ba1f1377e6f95'))
 paddle.fluid.io.load_params (ArgSpec(args=['executor', 'dirname', 'main_program', 'filename'], varargs=None, keywords=None, defaults=(None, None)), ('document', '41779819cef32f2246e83aebc5a002e2'))
 paddle.fluid.io.load_persistables (ArgSpec(args=['executor', 'dirname', 'main_program', 'filename'], varargs=None, keywords=None, defaults=(None, None)), ('document', '28df5bfe26ca7a077f91156abb0fe6d2'))
-paddle.fluid.io.save_inference_model (ArgSpec(args=['dirname', 'feeded_var_names', 'target_vars', 'executor', 'main_program', 'model_filename', 'params_filename', 'export_for_deployment'], varargs=None, keywords=None, defaults=(None, None, None, True)), ('document', '70f4f53f13572436ac72d1c8b5efeb9d'))
-paddle.fluid.io.load_inference_model (ArgSpec(args=['dirname', 'executor', 'model_filename', 'params_filename', 'pserver_endpoints'], varargs=None, keywords=None, defaults=(None, None, None)), ('document', '7a5255386075dac3c75b7058254fcdcb'))
+paddle.fluid.io.save_inference_model (ArgSpec(args=['dirname', 'feeded_var_names', 'target_vars', 'executor', 'main_program', 'model_filename', 'params_filename', 'export_for_deployment'], varargs=None, keywords=None, defaults=(None, None, None, True)), ('document', 'af82e1b5fe5764029905a191b987f63d'))
+paddle.fluid.io.load_inference_model (ArgSpec(args=['dirname', 'executor', 'model_filename', 'params_filename', 'pserver_endpoints'], varargs=None, keywords=None, defaults=(None, None, None)), ('document', '648f64d8fd81572eef34a69e533459ef'))
 paddle.fluid.io.PyReader.__init__ (ArgSpec(args=['self', 'feed_list', 'capacity', 'use_double_buffer', 'iterable'], varargs=None, keywords=None, defaults=(True, False)), ('document', '6adf97f83acf6453d4a6a4b1070f3754'))
 paddle.fluid.io.PyReader.decorate_batch_generator (ArgSpec(args=['self', 'reader', 'places'], varargs=None, keywords=None, defaults=(None,)), ('document', '4a072de39998ee4e0de33fcec11325a6'))
 paddle.fluid.io.PyReader.decorate_sample_generator (ArgSpec(args=['self', 'sample_generator', 'batch_size', 'drop_last', 'places'], varargs=None, keywords=None, defaults=(True, None)), ('document', '3db4b24d33fe4f711e303f9673dc5c6a'))

python/paddle/fluid/io.py

@@ -913,13 +913,32 @@ def save_inference_model(dirname,
     Examples:
         .. code-block:: python
 
-            exe = fluid.Executor(fluid.CPUPlace())
+            import paddle.fluid as fluid
+
             path = "./infer_model"
-            fluid.io.save_inference_model(dirname=path, feeded_var_names=['img'],
-                         target_vars=[predict_var], executor=exe)
 
-            # In this exsample, the function will prune the default main program
-            # to make it suitable for infering the `predict_var`. The pruned
+            # User defined network, here a softmax regresssion example
+            image = fluid.layers.data(name='img', shape=[1, 28, 28], dtype='float32')
+            label = fluid.layers.data(name='label', shape=[1], dtype='int64')
+            feeder = fluid.DataFeeder(feed_list=[image, label], place=fluid.CPUPlace())
+            predict = fluid.layers.fc(input=image, size=10, act='softmax')
+
+            loss = fluid.layers.cross_entropy(input=predict, label=label)
+            avg_loss = fluid.layers.mean(loss)
+
+            exe = fluid.Executor(fluid.CPUPlace())
+            exe.run(fluid.default_startup_program())
+
+            # Feed data and train process
+
+            # Save inference model. Note we don't save label and loss in this example
+            fluid.io.save_inference_model(dirname=path,
+                                          feeded_var_names=['img'],
+                                          target_vars=[predict],
+                                          executor=exe)
+
+            # In this example, the function will prune the default main program
+            # to make it suitable for infering the `predict` var. The pruned
             # inference program is going to be saved in the "./infer_model/__model__"
             # and parameters are going to be saved in separate files under folder
             # "./infer_model".
@@ -1075,7 +1094,7 @@ def load_inference_model(dirname,
             # if we need lookup table, we will use:
             fluid.io.load_inference_model(dirname=path, executor=exe, pserver_endpoints=endpoints)
 
-            # In this exsample, the inference program was saved in the
+            # In this example, the inference program was saved in the
             # "./infer_model/__model__" and parameters were saved in
             # separate files in ""./infer_model".
             # After getting inference program, feed target names and