diff --git a/onnx2fluid/README.md b/onnx2fluid/README.md
index a544fe3efa8e52b47676c9464ca2eb66b5055c23..95e4ad41101a6280ef6137944e15027255321de5 100644
--- a/onnx2fluid/README.md
+++ b/onnx2fluid/README.md
@@ -17,13 +17,13 @@ onnx2fluid支持将ONNX模型转换为PaddlePaddle模型，并用于预测，用
 在如下环境配置中测试成功:
 
 * python 3.5+
-* onnx == 1.4.0
-* paddlepaddle == 1.3.0 (可选，仅用于验证)
+* onnx == 1.4.1
+* paddlepaddle == 1.5.0 (可选，仅用于验证)
 
 使用[Anaconda](https://docs.anaconda.com/anaconda/install):
 ``` shell
 conda install -c conda-forge onnx
-pip install paddlepaddle==1.3.0
+pip install paddlepaddle==1.5.0
 ```
 
 ## 动手玩
@@ -49,6 +49,8 @@ onnx2fluid sample_1.onnx -t sample_1.npz
 
 ## 使用说明
 
+目前支持 **ONNX opset 9+** 的部分算子，对应PyTorch版本 **1.0/1.1(stable opset)**，更多兼容信息请参考[ONNX文档](https://github.com/onnx/onnx/blob/master/docs/Operators.md)
+
 onnx2fluid:
 
 ```shell
@@ -79,5 +81,5 @@ onnx2fluid.validate [-d] [-t test_data.npz] [-p 1e-3] /path/to/onnx/model.onnx
 
 ## 参考
 
-* PaddlePaddle [算子](http://www.paddlepaddle.org/documentation/docs/zh/1.4/api_cn/layers_cn.html)
-* PaddlePaddle [加载预测模型](http://www.paddlepaddle.org/documentation/docs/zh/1.4/api_guides/low_level/inference.html#id4)
+* PaddlePaddle [算子](http://www.paddlepaddle.org/documentation/docs/zh/1.5/api_cn/layers_cn.html)
+* PaddlePaddle [加载预测模型](http://www.paddlepaddle.org/documentation/docs/zh/1.5/api_guides/low_level/inference.html#id4)
diff --git a/onnx2fluid/examples/gen_some_samples.py b/onnx2fluid/examples/gen_some_samples.py
index 2c55f5c3939ea7d570d5bc97e1373b148db82a0e..52aacefeba70ef9705f02e3c5ce37247693b43f3 100644
--- a/onnx2fluid/examples/gen_some_samples.py
+++ b/onnx2fluid/examples/gen_some_samples.py
@@ -20,50 +20,56 @@ from onnx2fluid.torch_export_helper import export_onnx_with_validation
 prefix = 'sample_'
 idx = 0
 
-######### example: RNN ########
-#
-#class Model(nn.Module):
-#    def __init__(self):
-#        super(Model, self).__init__()
-#        self.rnn = nn.RNN(4, 6, 2)
-#
-#    def forward(self, x):
-#        y = x
-#        y, h = self.rnn(y)
-#        return y
-#
-#
-#model = Model()
-#model.eval()
-#xb = torch.rand((2, 3, 4))
-#yp = model(xb)
-#idx += 1
-#print('index: ', idx)
-#export_onnx_with_validation(model, [xb], prefix + str(idx),
-#                            ['x'], ['y'],
-#                            verbose=True, training=False)
+######## example: RNN ########
 
-######### example: random ########
-#
-#class Model(nn.Module):
-#    def __init__(self):
-#        super(Model, self).__init__()
-#
-#    def forward(self, x):
-#        y = torch.rand((2, 3)) # + torch.rand_like(xb)
-#        y = y + torch.randn((2, 3)) # + torch.randn_like(xb)
-#        return y
-#
-#
-#model = Model()
-#model.eval()
-#xb = torch.rand((2, 3))
-#yp = model(xb)
-#idx += 1
-#print('index: ', idx)
-#export_onnx_with_validation(model, [xb], prefix + str(idx),
-#                            ['x'], ['y'],
-#                            verbose=True, training=False)
+
+class Model(nn.Module):
+    def __init__(self):
+        super(Model, self).__init__()
+        self.gru = nn.GRU(4, 5, 3)
+        self.lstm = nn.LSTM(5, 6, 2)
+
+    def forward(self, x):
+        y = x
+        y, h = self.gru(y)
+        y, h = self.lstm(y)
+        return y
+
+
+model = Model()
+model.eval()
+xb = torch.rand((2, 3, 4))
+yp = model(xb)
+idx += 1
+print('index: ', idx)
+export_onnx_with_validation(model, [xb],
+                            prefix + str(idx), ['x'], ['y'],
+                            verbose=True,
+                            training=False)
+
+######## example: random ########
+
+
+class Model(nn.Module):
+    def __init__(self):
+        super(Model, self).__init__()
+
+    def forward(self, x):
+        y = torch.rand((2, 3))  # + torch.rand_like(xb)
+        y = y + torch.randn((2, 3))  # + torch.randn_like(xb)
+        return y
+
+
+model = Model()
+model.eval()
+xb = torch.rand((2, 3))
+yp = model(xb)
+idx += 1
+print('index: ', idx)
+export_onnx_with_validation(model, [xb],
+                            prefix + str(idx), ['x'], ['y'],
+                            verbose=True,
+                            training=False)
 
 ######## example: fc ########
 
@@ -175,7 +181,7 @@ class Model(nn.Module):
         super(Model, self).__init__()
         self.conv = nn.Conv2d(3, 8, 3)
         self.batch_norm = nn.BatchNorm2d(8)
-        self.pool = nn.AdaptiveAvgPool2d(2)
+        self.pool = nn.AdaptiveAvgPool2d(1)
 
     def forward(self, x):
         y = x
@@ -215,9 +221,10 @@ export_onnx_with_validation(model, [xb],
 #yp = model(xb)
 #idx += 1
 #print('index: ', idx)
-#export_onnx_with_validation(model, [xb], prefix + str(idx),
-#                            ['x'], ['y'],
-#                            verbose=True, training=False)
+#export_onnx_with_validation(
+#        model, [xb], prefix + str(idx),
+#        ['x'], ['y'],
+#        verbose=True, training=False)
 
 ######## example: empty ########
 
diff --git a/onnx2fluid/examples/onnx_model_zoo.sh b/onnx2fluid/examples/onnx_model_zoo.sh
index ca7fa9bf2c648d93f95c7cc5461fa677dc1c6a0e..ada80dfb81d32cbc5f148899500a2b4986129513 100755
--- a/onnx2fluid/examples/onnx_model_zoo.sh
+++ b/onnx2fluid/examples/onnx_model_zoo.sh
@@ -24,14 +24,14 @@ bvlc_alexnet()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for npz in "$bn_tar"/*.npz
+	for npz in "$bn_tar/"*.npz
 	do
 		echo "converting $npz ..."
 		python convert_data_npz.py "$npz" data_0 prob_1 -s
 		python -m onnx2fluid.validation $validate_flags1 -t "$npz"
 		python -m onnx2fluid.validation $validate_flags2 -t "$npz"
 	done
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data_0 prob_1
@@ -54,7 +54,7 @@ bvlc_googlenet()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" data_0 prob_1
@@ -77,7 +77,7 @@ bvlc_reference_caffenet()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" data_0 prob_1
@@ -100,7 +100,7 @@ bvlc_reference_rcnn_ilsvrc13()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" data_0 fc-rcnn_1
@@ -123,14 +123,14 @@ densenet121()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for npz in "$bn_tar"/*.npz
+	for npz in "$bn_tar/"*.npz
 	do
 		echo "converting $npz ..."
 		python convert_data_npz.py "$npz" data_0 fc6_1 -s
 		python -m onnx2fluid.validation $validate_flags1 -t "$npz"
 		python -m onnx2fluid.validation $validate_flags2 -t "$npz"
 	done
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" data_0 fc6_1
@@ -153,7 +153,7 @@ emotion_ferplus()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" Input3 Plus692_Output_0
@@ -176,14 +176,14 @@ inception_v1()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for npz in "$bn_tar"/*.npz
+	for npz in "$bn_tar/"*.npz
 	do
 		echo "converting $npz ..."
 		python convert_data_npz.py "$npz" data_0 prob_1 -s
 		python -m onnx2fluid.validation $validate_flags1 -t "$npz"
 		python -m onnx2fluid.validation $validate_flags2 -t "$npz"
 	done
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data_0 prob_1
@@ -206,14 +206,14 @@ inception_v2()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for npz in "$bn_tar"/*.npz
+	for npz in "$bn_tar/"*.npz
 	do
 		echo "converting $npz ..."
 		python convert_data_npz.py "$npz" data_0 prob_1 -s
 		python -m onnx2fluid.validation $validate_flags1 -t "$npz"
 		python -m onnx2fluid.validation $validate_flags2 -t "$npz"
 	done
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data_0 prob_1
@@ -236,7 +236,7 @@ mobilenet()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data mobilenetv20_output_flatten0_reshape0
@@ -259,7 +259,7 @@ resnet18()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data resnetv15_dense0_fwd
@@ -282,14 +282,14 @@ resnet50()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for npz in "$bn_tar"/*.npz
+	for npz in "$bn_tar/"*.npz
 	do
 		echo "converting $npz ..."
 		python convert_data_npz.py "$npz" gpu_0/data_0 gpu_0/softmaxout_1 -s
 		python -m onnx2fluid.validation $validate_flags1 -t "$npz"
 		python -m onnx2fluid.validation $validate_flags2 -t "$npz"
 	done
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" gpu_0/data_0 gpu_0/softmaxout_1
@@ -312,7 +312,7 @@ resnet100_arcface()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data fc1
@@ -335,7 +335,7 @@ resnet101_duc()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data seg_loss
@@ -358,7 +358,7 @@ resnet152()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data resnetv27_dense0_fwd
@@ -381,7 +381,7 @@ shufflenet()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" gpu_0/data_0 gpu_0/softmax_1
@@ -404,7 +404,7 @@ squeezenet()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" data_0 softmaxout_1
@@ -427,7 +427,7 @@ squeezenet1v1()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data squeezenet0_flatten0_reshape0
@@ -448,10 +448,10 @@ ssd()
 	rm -rf "$bn_tar/"
 	echo "extracting ..."
 	mkdir "$bn_tar"
-	tar xf "$fn_tar" -C "$bn_tar"/
+	tar xf "$fn_tar" -C "$bn_tar/"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" image bboxes,labels,scores
@@ -474,7 +474,7 @@ tiny_yolov2()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" image grid
@@ -497,7 +497,7 @@ vgg16bn()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -y
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" data vgg0_dense2_fwd
@@ -520,7 +520,7 @@ vgg19()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" data_0 prob_1
@@ -543,7 +543,7 @@ yolov3()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model" -x #
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir ..."
 		python convert_data_pb.py "$pb_dir" input_1:01,image_shape:01 yolonms_layer_1/ExpandDims_1:0,yolonms_layer_1/ExpandDims_3:0,yolonms_layer_1/concat_2:0
@@ -566,7 +566,7 @@ zfnet512()
 	tar xf "$fn_tar"
 
 	python -m onnx2fluid $convert_flags "$fn_model"
-	for pb_dir in "$bn_tar"/*/
+	for pb_dir in "$bn_tar/"*/
 	do
 		echo "converting $pb_dir"
 		python convert_data_pb.py "$pb_dir" gpu_0/data_0 gpu_0/softmax_1
diff --git a/onnx2fluid/onnx2fluid/conversion.py b/onnx2fluid/onnx2fluid/conversion.py
index b566936430de98103ca4671f125e620fae489b5f..a7fee9cd45bf8c1220bdcb520623bd64a8d147bd 100644
--- a/onnx2fluid/onnx2fluid/conversion.py
+++ b/onnx2fluid/onnx2fluid/conversion.py
@@ -17,6 +17,22 @@ __all__ = [
 DEFAULT_ONNX_OPSET_VERSION = 9
 
 
+def make_var_name(name):
+    """
+    make a valid variable name in Python code and filename in filesystem
+    """
+
+    if name == '':
+        return '_'
+    if name[0].isdigit():
+        return 'var_' + name
+    for s in ' \\|/:.-':
+        name = name.replace(s, '_')
+    if name.startswith('_'):
+        name = 'var' + name
+    return name
+
+
 def convert(onnx_model_filename,
             save_dir,
             model_basename='model.py',
@@ -30,6 +46,12 @@ def convert(onnx_model_filename,
     convert an ONNX model to Paddle fluid Python code and desc pb
     """
 
+    assert isinstance(onnx_model_filename, str)
+    assert isinstance(save_dir, str)
+    assert isinstance(model_basename, str)
+    assert isinstance(model_func_name, str)
+    assert onnx_opset_version is None or isinstance(onnx_opset_version, int)
+
     import onnx
 
     from onnx.checker import ValidationError
@@ -41,7 +63,6 @@ def convert(onnx_model_filename,
     from .onnx_utils import inferred_model_value_info
     from .onnx_utils import polish_model
     from .writer import Program, Writer
-    from .writer import make_var_name
 
     logger = logging.getLogger('convert')
 
@@ -88,17 +109,21 @@ def convert(onnx_model_filename,
     fluid_writer = Writer()
 
     # model components
-    #    graph_name = onnx_graph.name
-    graph_inputs = [value.name for value in onnx_graph.input]
-    graph_outputs = [value.name for value in onnx_graph.output]
-    graph_params = []
-    graph_value_infos = inferred_model_value_info(onnx_model)
+    inp_vars = [make_var_name(value.name) for value in onnx_graph.input]
+    out_vars = [make_var_name(value.name) for value in onnx_graph.output]
+    par_vars = []
+    value_infos = inferred_model_value_info(onnx_model)
+    value_infos = {
+        make_var_name(key): value
+        for key, value in value_infos.items()
+    }
 
     # prepare additional value_info
     # for weights
     for name, weight in graph_weights(onnx_graph):
-        value_info = graph_value_infos[name]
-        value_info['embeded_as'] = []
+        var_name = make_var_name(name)
+        value_info = value_infos[var_name]
+        value_info['embedded_as'] = []
         value_info['get_weight'] = (lambda w: lambda: w.tolist())(
             weight)  # lazy getter
 
@@ -108,19 +133,23 @@ def convert(onnx_model_filename,
     topo = 'forward'
     for name, domain, op_type, inputs, outputs, attrs in graph_ops(onnx_graph,
                                                                    topo=topo):
-        logger.debug('translating op %s %s::%s ...', name, domain, op_type)
+        op_name = make_var_name(name)
+        inputs = [make_var_name(val) for val in inputs]
+        outputs = [make_var_name(val) for val in outputs]
+        logger.debug('translating op %s(%s) %s::%s ...', name, op_name, domain,
+                     op_type)
         if domain == DEFAULT_OP_DOMAIN:
             domain = ''
         try:
             fluid_writer.emit_op(
                 fluid_program,
-                name,
+                op_name,
                 domain,
                 op_type,
                 inputs,
                 outputs,
                 attrs,
-                graph_value_infos,
+                value_infos,
                 embed_params=embed_params,
             )
         except BaseException as e:
@@ -133,17 +162,16 @@ def convert(onnx_model_filename,
                 len(fluid_program.op_descs))
 
     # type-shape info copy
-    for name, value_info in graph_value_infos.items():
-        var_name = make_var_name(name)
+    for var_name, value_info in value_infos.items():
         fluid_program.VarTypeShapeInfo(var_name, value_info,
                                        remove_batch=False)  #
-    bad_var_names = []
+    bad_vars = []
     for var_name, var_desc in fluid_program.var_descs.items():
         if not var_desc.type.lod_tensor.HasField('tensor'):
-            bad_var_names.append(var_name)
-    if len(bad_var_names) > 0:
+            bad_vars.append(var_name)
+    if len(bad_vars) > 0:
         logger.warning('type-shape not infered for var %s ...',
-                       ', '.join(bad_var_names[:5]))
+                       ', '.join(bad_vars[:5]))
         logger.warning('this causes little problem for PaddlePaddle, '
                        'but Paddle Mobile may not infer correctly')
         logger.warning('please consider running validation with -i '
@@ -151,40 +179,41 @@ def convert(onnx_model_filename,
 
     # weight writer
     for name, weight in graph_weights(onnx_graph):
-        graph_params.append(name)
-        value_info = graph_value_infos[name]
-        var_names = value_info.get('embeded_as', [])
-        if var_names:
-            if len(var_names) > 1:
+        var_name = make_var_name(name)
+        par_vars.append(var_name)
+        value_info = value_infos[var_name]
+        embedded_names = value_info.get('embedded_as', [])
+        if embedded_names:
+            if len(embedded_names) > 1:
                 logger.info(
                     'weight %s is shared between ops, more disk space will be consumed',
                     name)
             logger.debug('saving weight %s(%s[%d], %dB) as %s ...', name,
-                         weight.dtype, weight.size, weight.nbytes, var_names)
-            for var_name in var_names:  # multiple references
+                         weight.dtype, weight.size, weight.nbytes,
+                         embedded_names)
+            for embedded_name in embedded_names:  # multiple references
                 fluid_writer.write_weight(
-                    weight, shutil.os.path.join(save_dir, var_name))
+                    weight, shutil.os.path.join(save_dir, embedded_name))
         else:
             logger.debug('saving weight %s(%s[%d], %dB) to %s ...', name,
-                         weight.dtype, weight.size, weight.nbytes,
-                         make_var_name(name))
-            fluid_writer.write_weight(
-                weight, shutil.os.path.join(save_dir, make_var_name(name)))
-        fluid_writer.emit_param(fluid_program, name, value_info)
+                         weight.dtype, weight.size, weight.nbytes, var_name)
+            fluid_writer.write_weight(weight,
+                                      shutil.os.path.join(save_dir, var_name))
+        fluid_writer.emit_param(fluid_program, var_name, value_info)
     param_codes = fluid_program.codes
     fluid_program.codes = []
-    logger.info('%d weights converted', len(graph_params))
+    logger.info('%d weights converted', len(par_vars))
 
     # input writer
     external_inputs = []
-    for name in graph_inputs:
-        if name not in graph_params:
-            value_info = graph_value_infos[name]
+    for var_name in inp_vars:
+        if var_name not in par_vars:
+            value_info = value_infos[var_name]
             assert value_info['external']
-            external_inputs.append(name)
+            external_inputs.append(var_name)
     fluid_writer.emit_inputs(fluid_program,
                              external_inputs,
-                             graph_value_infos,
+                             value_infos,
                              remove_batch=False)  # TODO:
     input_codes = fluid_program.codes
     fluid_program.codes = []
@@ -192,11 +221,11 @@ def convert(onnx_model_filename,
 
     # output writer
     external_outputs = []
-    for name in graph_outputs:
-        if name not in graph_params:
-            value_info = graph_value_infos[name]
+    for var_name in out_vars:
+        if var_name not in par_vars:
+            value_info = value_infos[var_name]
             assert value_info['external']
-            external_outputs.append(name)
+            external_outputs.append(var_name)
     fluid_writer.emit_outputs(fluid_program, external_outputs)
     output_codes = [''] + fluid_program.codes  # add an empty line
     fluid_program.codes = []
@@ -204,10 +233,18 @@ def convert(onnx_model_filename,
 
     # code generation
     header_codes = fluid_writer.header_code(
-        model_func_name, 'From: {}'.format(onnx_model_filename))
+        model_func_name,
+        'From: {}'.format(onnx_model_filename),
+    )
     code_filename = shutil.os.path.join(save_dir, model_basename)
-    fluid_writer.write_code_file(code_filename, header_codes, input_codes,
-                                 param_codes, op_codes, output_codes)
+    fluid_writer.write_code_file(
+        code_filename,
+        header_codes,
+        input_codes,
+        param_codes,
+        op_codes,
+        output_codes,
+    )
     logger.info('code saved to %s, factory function: %s', code_filename,
                 model_func_name)
 
diff --git a/onnx2fluid/onnx2fluid/onnx_utils.py b/onnx2fluid/onnx2fluid/onnx_utils.py
index 1c86b4bbd7b08d58b17405c8d07ad8efcbdfb3f7..e8b5a472e312439f97606c02e5cc4f7f657ce4c2 100644
--- a/onnx2fluid/onnx2fluid/onnx_utils.py
+++ b/onnx2fluid/onnx2fluid/onnx_utils.py
@@ -87,6 +87,9 @@ def get_attribute_value2(attr):
     get_attribute_value enhanced
     """
 
+    assert isinstance(
+        attr, onnx.AttributeProto), 'attr is not a AttributeProto instance'
+
     if attr.type == onnx.AttributeProto.TENSOR:
         dtype = np.dtype(TENSOR_TYPE_TO_NP_TYPE[attr.t.data_type])
         data = attr.t.raw_data
@@ -106,6 +109,9 @@ def tensor_dtype(tensor):
     get ONNX tensor in np.dtype
     """
 
+    assert isinstance(
+        tensor, onnx.ValueInfoProto), 'tensor is not a ValueInfoProto instance'
+
     return TENSOR_TYPE_TO_NP_TYPE[tensor.type.tensor_type.elem_type]
 
 
@@ -114,6 +120,9 @@ def tensor_shape(tensor):
     get ONNX tensor shape
     """
 
+    assert isinstance(
+        tensor, onnx.ValueInfoProto), 'tensor is not a ValueInfoProto instance'
+
     return tuple([dim.dim_value for dim in tensor.type.tensor_type.shape.dim])
 
 
@@ -122,6 +131,8 @@ def node_attrs(node):
     convert ONNX node attributes to dict
     """
 
+    assert isinstance(node, onnx.NodeProto), 'node is not a NodeProto instance'
+
     return {attr.name: get_attribute_value2(attr)
             for attr in node.attribute}  # dict
 
@@ -224,9 +235,8 @@ def graph_ops(graph, topo='default'):
     generator for ONNX node graph with given topology
     """
 
-    if not isinstance(graph, onnx.GraphProto):
-        logger.error('graph is not a GraphProto instance')
-        return
+    assert isinstance(graph,
+                      onnx.GraphProto), 'graph is not a GraphProto instance'
 
     return node_iter(graph.node, node_topo(graph.node, topo))
 
@@ -236,9 +246,8 @@ def graph_weights(graph):
     generator for weights of an ONNX model
     """
 
-    if not isinstance(graph, onnx.GraphProto):
-        logger.error('graph is not a GraphProto instance')
-        return
+    assert isinstance(graph,
+                      onnx.GraphProto), 'graph is not a GraphProto instance'
 
     for initializer in graph.initializer:
         name = initializer.name
@@ -251,6 +260,9 @@ def inferred_model_value_info(model):
     collect value/type info for an ONNX model
     """
 
+    assert isinstance(model,
+                      onnx.ModelProto), 'model is not a ModelProto instance'
+
     model = infer_shapes(model)
     graph = model.graph
     value_info = Dict()
@@ -353,6 +365,10 @@ def optimize_model_skip_op_for_inference(model, op_list=None):
     """
     skip ops can be bypassed for inference
     """
+
+    assert isinstance(model,
+                      onnx.ModelProto), 'model is not a ModelProto instance'
+
     if op_list is None:
         op_list = ('Dropout', 'Identity')
 
@@ -415,6 +431,9 @@ def optimize_model_strip_initializer(model, keep_input_only=True):
     strip weights for inference
     """
 
+    assert isinstance(model,
+                      onnx.ModelProto), 'model is not a ModelProto instance'
+
     nodes = model.graph.node
     input_refs, output_refs = build_value_refs(nodes)
     out_names = [val.name for val in model.graph.output]
@@ -456,6 +475,9 @@ def optimize_model_cast(model):
     strip cascade and unecessary onnx::Cast-9:
     """
 
+    assert isinstance(model,
+                      onnx.ModelProto), 'model is not a ModelProto instance'
+
     nodes = model.graph.node
     input_refs, output_refs = build_value_refs(nodes)
     value_info = inferred_model_value_info(model)
@@ -513,6 +535,9 @@ def optimize_model_slice(model):
     strip cascade and unecessary onnx::Slice-1:9
     """
 
+    assert isinstance(model,
+                      onnx.ModelProto), 'model is not a ModelProto instance'
+
     nodes = model.graph.node
     input_refs, output_refs = build_value_refs(nodes)
 
diff --git a/onnx2fluid/onnx2fluid/symbolic.py b/onnx2fluid/onnx2fluid/symbolic.py
index a1cee35642c0ba108e60e097b940c68c773335f9..139d3bcef96159e275373def886ae7e4f37b3c7f 100644
--- a/onnx2fluid/onnx2fluid/symbolic.py
+++ b/onnx2fluid/onnx2fluid/symbolic.py
@@ -50,6 +50,9 @@ DEFAULT_OP_MAPPING = {
              dict(), None, None, False],
         ## unary ops ##
         'Abs': ['abs', ['X'], ['Out']],
+        'Acos': ['acos', ['X'], ['Out']],
+        'Asin': ['asin', ['X'], ['Out']],
+        'Atan': ['atan', ['X'], ['Out']],
         'ArgMax': ['argmax', ['X'], ['Out'], dict(keepdims='')],
         'ArgMin': ['argmin', ['X'], ['Out'], dict(keepdims='')],
         'Ceil': ['ceil', ['X'], ['Out']],
@@ -144,52 +147,36 @@ DEFAULT_IOA_CONSTRAINTS = {
 }
 
 
-def _make_var_name(name):
-    """
-    make a valid variable name in Python code and in filesystem
-    """
-
-    if name == '':
-        return '_'
-    if name[0].isdigit():
-        return 'var_' + name
-    for s in ' \\|/:-':  #
-        name = name.replace(s, '_')
-    if name.startswith('_'):
-        name = 'var' + name
-    return name
+def _dtype(value_infos, name):
+    return _np.dtype(value_infos[name]['dtype'])
 
 
-def _dtype(value_infos, val_name):
-    return _np.dtype(value_infos[val_name]['dtype'])
-
-
-def _dtype_or_none(value_infos, val_name):
-    if val_name not in value_infos:
+def _dtype_or_none(value_infos, name):
+    if name not in value_infos:
         return None
-    value_info = value_infos[val_name]
+    value_info = value_infos[name]
     if 'dtype' not in value_info:
         return None
     return _np.dtype(value_info['dtype'])
 
 
-def _shape(value_infos, val_name):
-    return list(value_infos[val_name]['shape'])
+def _shape(value_infos, name):
+    return list(value_infos[name]['shape'])
 
 
-def _shape_or_none(value_infos, val_name):
-    if val_name not in value_infos:
+def _shape_or_none(value_infos, name):
+    if name not in value_infos:
         return None
-    value_info = value_infos[val_name]
+    value_info = value_infos[name]
     if 'shape' not in value_info:
         return None
     return list(value_info['shape'])
 
 
-def _const_weight_or_none(value_infos, val_name):
-    if val_name not in value_infos:
+def _const_weight_or_none(value_infos, name):
+    if name not in value_infos:
         return None
-    value_info = value_infos[val_name]
+    value_info = value_infos[name]
     const_value = value_info.get('const_value', None)
     if const_value is not None:
         return const_value
@@ -199,11 +186,11 @@ def _const_weight_or_none(value_infos, val_name):
     return None
 
 
-def _check_embeddable(value_infos, *val_names):
+def _check_embeddable(value_infos, *names):
     keyword = 'get_weight'
-    for val_name in val_names:
-        if keyword not in value_infos[val_name]:
-            _logger.warning('parameter %s not embeddable', val_name)
+    for name in names:
+        if keyword not in value_infos[name]:
+            _logger.warning('parameter %s not embeddable', name)
             return False
     return True
 
@@ -239,12 +226,10 @@ def _default(prog, op_type, inputs, outputs, attrs, *args, name='', **kwargs):
     fluid_attrs = default_attrs.copy()
     fluid_attrs.update(mapped_attrs)  # as new attrs
 
-    val_inps = inputs if input_perm is None else map(inputs.__getitem__,
-                                                     input_perm)
-    val_outs = outputs if output_perm is None else map(outputs.__getitem__,
-                                                       output_perm)
-    var_inps = [_make_var_name(val) for val in val_inps]
-    var_outs = [_make_var_name(val) for val in val_outs]
+    var_inps = inputs if input_perm is None else list(
+        map(inputs.__getitem__, input_perm))
+    var_outs = outputs if output_perm is None else list(
+        map(outputs.__getitem__, output_perm))
     arg_name = ', name={}'.format(
         repr(name)) if fill_name_field and name else ''
     arg_attrs = [
@@ -277,9 +262,7 @@ def _default(prog, op_type, inputs, outputs, attrs, *args, name='', **kwargs):
 def _assign(prog, mapping):
     fluid_op = 'assign'
 
-    for val_dst, val_src in mapping.items():
-        var_dst = _make_var_name(val_dst)
-        var_src = _make_var_name(val_src)
+    for var_dst, var_src in mapping.items():
         prog.Code('{} = {} # assign'.format(var_dst, var_src))
         #        prog.Code('{} = layers.{}({})'
         #                  .format(var_dst,
@@ -295,18 +278,18 @@ def _assign(prog, mapping):
         )
 
 
-def _zeros_like(prog, val_ref, val_out, value_infos):
+def _zeros_like(prog, var_ref, var_out, value_infos):
     prog.Op(
         '',
         'Sub',
-        [val_ref, val_ref],
-        [val_out],  # val
+        [var_ref, var_ref],
+        [var_out],
         {'axis': 0},
         value_infos,
     )
 
 
-def _pad_if_asymmetric(prog, pads, val_name, value_infos):  # pads: SSEE
+def _pad_if_asymmetric(prog, pads, var_name, value_infos):  # pads: SSEE
     assert len(pads) & 1 == 0
     ndims = len(pads) // 2
     symmetric = True
@@ -315,36 +298,29 @@ def _pad_if_asymmetric(prog, pads, val_name, value_infos):  # pads: SSEE
             symmetric = False
             break
     if symmetric:
-        return pads[:ndims], val_name
+        return pads[:ndims], var_name
 
-    val_padded = val_name + '_padded'  # explicit variable
+    var_padded = var_name + '_padded'  # explicit variable
     prog.Op(
         '',
         'Pad',
-        [val_name],
-        [val_padded],  # val
+        [var_name],
+        [var_padded],
         {
             'mode': 'constant',
             'value': 0.,
             'pads': pads,
         },
         value_infos=value_infos,
-        name=val_padded,
+        name=var_padded,
     )
-    return [0] * ndims, val_padded
+    return [0] * ndims, var_padded
 
 
 def _adaptive_pool(prog, pool_type, inputs, outputs, attrs, name=''):
     # I/O
-    val_x, = inputs
-    val_y, = outputs[:1]
-    var_x = _make_var_name(val_x)
-    var_y = _make_var_name(val_y)
-
-    has_indices = len(outputs) > 1
-    if has_indices:
-        val_indices = outputs[1]
-        var_indices = _make_var_name(val_indices)
+    var_x, = inputs
+    var_y, var_indices = (outputs + [None] * 1)[:2]
 
     # interpretation
     pool_size = attrs['output_size']  # required
@@ -361,28 +337,28 @@ def _adaptive_pool(prog, pool_type, inputs, outputs, attrs, name=''):
               ', pool_type={}'
               '{})'.format(
                   var_y,
-                  ', {}'.format(var_indices) if has_indices else '',
+                  ', {}'.format(var_indices) if var_indices else '',
                   fluid_op,
                   var_x,
                   # attrs
-                  has_indices,
+                  bool(var_indices),
                   pool_size,
                   repr(pool_type),
                   name_attr,
               ))
     fluid_op = 'pool{}d'.format(poolnd)
     prog.VarDesc(var_y)
-    if has_indices:
+    if var_indices:
         prog.VarDesc(var_indices)
     prog.OpDesc(
         fluid_op,
         ([var_x], 'X'),
-        ([var_y] + ([var_indices] if has_indices else []), 'Out', 'Indices'),
+        ([var_y] + ([var_indices] if var_indices else []), 'Out', 'Indices'),
         {
             'global_pooling': False,
             'adaptive': True,
             'exclusive': True,
-            'require_index': has_indices,
+            'require_index': bool(var_indices),
             'pooling_type': pool_type,
             'ksize': pool_size,
         },
@@ -391,14 +367,12 @@ def _adaptive_pool(prog, pool_type, inputs, outputs, attrs, name=''):
 
 def _global_pool(prog, pool_type, inputs, outputs, attrs, value_infos, name=''):
     # I/O
-    val_x, = inputs
-    val_y, = outputs
-    var_x = _make_var_name(val_x)
-    var_y = _make_var_name(val_y)
+    var_x, = inputs
+    var_y, = outputs
 
     # interpretation
-    input_shape = _shape_or_none(value_infos, val_x)
-    output_shape = _shape_or_none(value_infos, val_y)
+    input_shape = _shape_or_none(value_infos, var_x)
+    output_shape = _shape_or_none(value_infos, var_y)
     assert input_shape is not None or output_shape is not None, 'poolnd not inferred'  # NC...
     if input_shape is not None:
         poolnd = len(input_shape) - 2  # NC...
@@ -436,14 +410,8 @@ def _global_pool(prog, pool_type, inputs, outputs, attrs, value_infos, name=''):
 
 def _pool(prog, pool_type, inputs, outputs, attrs, value_infos, name=''):
     # I/O
-    val_x, = inputs
-    val_y, = outputs[:1]
-    var_y = _make_var_name(val_y)
-
-    has_indices = len(outputs) > 1
-    if has_indices:
-        val_indices = outputs[1]
-        var_indices = _make_var_name(val_indices)
+    var_x, = inputs
+    var_y, var_indices = (outputs + [None] * 1)[:2]
 
     # interpretation
     assert attrs.get(
@@ -457,8 +425,7 @@ def _pool(prog, pool_type, inputs, outputs, attrs, value_infos, name=''):
     strides = attrs.get('strides', [1] * poolnd)  # optional
     ceil_mode = bool(attrs.get('ceil_mode', 0))  # optional
     pads = attrs.get('pads', [0] * (poolnd * 2))  # optional
-    paddings, val_x = _pad_if_asymmetric(prog, pads, val_x, value_infos)
-    var_x = _make_var_name(val_x)
+    paddings, var_x = _pad_if_asymmetric(prog, pads, var_x, value_infos)
     name_attr = ', name={}'.format(repr(name)) if name else ''
 
     # generation
@@ -481,17 +448,17 @@ def _pool(prog, pool_type, inputs, outputs, attrs, value_infos, name=''):
                   name_attr,
               ))
     prog.VarDesc(var_y)
-    if has_indices:
+    if var_indices:
         prog.VarDesc(var_indices)
     prog.OpDesc(
         fluid_op,
         ([var_x], 'X'),
-        ([var_y] + ([var_indices] if has_indices else []), 'Out', 'Indices'),
+        ([var_y] + ([var_indices] if var_indices else []), 'Out', 'Indices'),
         {
             'global_pooling': False,
             'adaptive': False,
             'exclusive': True,
-            'require_index': has_indices,
+            'require_index': bool(var_indices),
             'pooling_type': pool_type,
             'ksize': pool_size,
             'strides': strides,
@@ -503,11 +470,8 @@ def _pool(prog, pool_type, inputs, outputs, attrs, value_infos, name=''):
 
 def _roi_pool(prog, fluid_op, inputs, outputs, attrs, value_infos, name):
     # I/O
-    val_x, val_rois = inputs
-    val_y, = outputs
-    var_x = _make_var_name(val_x)
-    var_rois = _make_var_name(val_rois)
-    var_y = _make_var_name(val_y)
+    var_x, var_rois = inputs
+    var_y, = outputs
 
     # interpretation
     spatial_scale = attrs['spatial_scale']  # required
@@ -536,7 +500,7 @@ def _roi_pool(prog, fluid_op, inputs, outputs, attrs, value_infos, name):
               '{})'.format(
                   var_y,
                   fluid_op,
-                  val_x,
+                  var_x,
                   var_rois,
                   # attrs
                   spatial_scale,
@@ -546,7 +510,7 @@ def _roi_pool(prog, fluid_op, inputs, outputs, attrs, value_infos, name):
               ))
     prog.VarDesc(var_y)
     if is_max_pool:
-        var_argmax = _make_var_name(name + '.argmax')  # hidden variable
+        var_argmax = name + '.argmax'  # hidden variable
         prog.VarDesc(var_argmax)
     prog.OpDesc(
         fluid_op,
@@ -558,19 +522,17 @@ def _roi_pool(prog, fluid_op, inputs, outputs, attrs, value_infos, name):
 
 def _interpolate(prog, inputs, outputs, attrs, value_infos, name=''):
     # I/O
-    val_x, val_scales = inputs
-    val_y, = outputs
-    var_x = _make_var_name(val_x)
-    var_y = _make_var_name(val_y)
+    var_x, var_scales = inputs
+    var_y, = outputs
 
     # interpretation
     # output shape
-    out_shape_ = _shape_or_none(value_infos, val_y)
+    out_shape_ = _shape_or_none(value_infos, var_y)
     if out_shape_ is not None:
         assert len(out_shape_) == 4, 'only 4-D Tensor as X and Y supported'
         out_shape_ = out_shape_[2:]
     # try scales
-    scales = _const_weight_or_none(value_infos, val_scales)
+    scales = _const_weight_or_none(value_infos, var_scales)
     if scales is not None:
         assert len(scales) == 4, 'only 4-D Tensor as X and Y supported'
         assert scales[0] == 1 and scales[
@@ -585,7 +547,7 @@ def _interpolate(prog, inputs, outputs, attrs, value_infos, name=''):
     else:
         out_shape = None
         if out_shape_ is None:
-            in_shape = _shape_or_none(value_infos, val_x)
+            in_shape = _shape_or_none(value_infos, var_x)
             assert in_shape is not None, 'out_shape required but not inferrable'
             assert len(in_shape) == 4, 'only 4-D Tensor as X and Y supported'
             out_shape_ = [in_shape[2] * scale, in_shape[3] * scale]
@@ -642,10 +604,8 @@ def AffineGrid(prog, inputs, outputs, attrs, *args, name='', **kwargs):
     """
 
     # I/O
-    val_theta, = inputs
-    val_grid, = outputs
-    var_theta = _make_var_name(val_theta)
-    var_grid = _make_var_name(val_grid)
+    var_theta, = inputs
+    var_grid, = outputs
 
     # interpretation
     fluid_op = 'affine_grid'
@@ -701,10 +661,8 @@ def BatchNormalization(prog,
     """
 
     # I/O
-    val_x, val_scale, val_b, val_mean, val_var = inputs
-    val_y, = outputs
-    var_x = _make_var_name(val_x)
-    var_y = _make_var_name(val_y)
+    var_x, var_scale, var_b, var_mean, var_var = inputs
+    var_y, = outputs
     var_saved_mean = name + '.saved_mean'  # dummy output
     var_saved_variance = name + '.saved_variance'  # dummy output
 
@@ -714,28 +672,28 @@ def BatchNormalization(prog,
     epsilon = attrs.get('epsilon', 1e-5)  # optional
     name_attr = ', name={}'.format(repr(name)) if name else ''
     if embed_params:
-        embed_params = _check_embeddable(value_infos, val_scale, val_b,
-                                         val_mean, val_var)
+        embed_params = _check_embeddable(value_infos, var_scale, var_b,
+                                         var_mean, var_var)
         if not embed_params and name:
             _logger.warning('for op  %s(%s -> BatchNormalization -> %s)', name,
                             inputs, outputs)
             _logger.warning('broken Python code will be generated')
     if embed_params:
         assert name != ''
-        var_scale = name + '.w_0'
-        var_b = name + '.b_0'
-        var_mean = name + '.w_1'
-        var_var = name + '.w_2'
-        value_infos[val_scale]['embeded_as'].append(var_scale)
-        value_infos[val_b]['embeded_as'].append(var_b)
-        value_infos[val_mean]['embeded_as'].append(var_mean)
-        value_infos[val_var]['embeded_as'].append(var_var)
+        embedded_scale = name + '.w_0'
+        embedded_b = name + '.b_0'
+        embedded_mean = name + '.w_1'
+        embedded_var = name + '.w_2'
+        value_infos[var_scale]['embedded_as'].append(embedded_scale)
+        value_infos[var_b]['embedded_as'].append(embedded_b)
+        value_infos[var_mean]['embedded_as'].append(embedded_mean)
+        value_infos[var_var]['embedded_as'].append(embedded_var)
+        var_scale = embedded_scale
+        var_b = embedded_b
+        var_mean = embedded_mean
+        var_var = embedded_var
         param_attr = ''
     else:
-        var_scale = _make_var_name(val_scale)
-        var_b = _make_var_name(val_b)
-        var_mean = _make_var_name(val_mean)
-        var_var = _make_var_name(val_var)
         param_attr = (', param_attr={}, bias_attr={}'
                       ', moving_mean_name={}, moving_variance_name={}').format(
                           repr(var_scale), repr(var_b), repr(var_mean),
@@ -780,16 +738,14 @@ def Cast(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
     """
 
     # I/O
-    val_input, = inputs
-    val_output, = outputs
-    var_input = _make_var_name(val_input)
-    var_output = _make_var_name(val_output)
+    var_input, = inputs
+    var_output, = outputs
 
     # interpretation
     dtype = attrs['to']  # required
     if not isinstance(dtype, _np.dtype):  # additional: possible np.dtype
         dtype = TENSOR_TYPE_TO_NP_TYPE[dtype]
-    output_dtype = _dtype_or_none(value_infos, val_output)
+    output_dtype = _dtype_or_none(value_infos, var_output)
     if output_dtype is not None:
         assert dtype == output_dtype, 'dtype of to unmatches output'
 
@@ -812,7 +768,7 @@ def Cast(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
         ([var_output], 'Out'),
         {
             'in_dtype': prog.Dtype(_dtype(value_infos,
-                                          val_input)),  # holy, required
+                                          var_input)),  # holy, required
             'out_dtype': prog.Dtype(dtype),
         },
     )
@@ -824,9 +780,7 @@ def Concat(prog, inputs, outputs, attrs, *args, name='', **kwargs):
     """
 
     # I/O
-    val_concat_result, = outputs
-    var_inps = [_make_var_name(val) for val in inputs]
-    var_concat_result = _make_var_name(val_concat_result)
+    var_ret, = outputs
 
     # interpretation
     fluid_op = 'concat'
@@ -837,18 +791,18 @@ def Concat(prog, inputs, outputs, attrs, *args, name='', **kwargs):
     prog.Code('{} = layers.{}({}'
               ', axis={}'
               '{})'.format(
-                  var_concat_result,
+                  var_ret,
                   fluid_op,
-                  '[' + ', '.join(var_inps) + ']',
+                  '[' + ', '.join(inputs) + ']',
                   # attrs
                   axis,
                   name_attr,
               ))
-    prog.VarDesc(var_concat_result)
+    prog.VarDesc(var_ret)
     prog.OpDesc(
         fluid_op,
-        (var_inps, *(['X'] * len(var_inps))),
-        ([var_concat_result], 'Out'),
+        (inputs, *(['X'] * len(inputs))),
+        ([var_ret], 'Out'),
         {'axis': axis},
     )
 
@@ -860,13 +814,12 @@ def Constant(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
 
     # I/O
     assert len(inputs) == 0, 'constant op accept no inputs'
-    val_output, = outputs
-    var_output = _make_var_name(val_output)
+    var_output, = outputs
 
     # interpretation
     value = attrs['value']  # required
     dtype = _np.dtype(value.dtype)
-    output_dtype = _dtype_or_none(value_infos, val_output)
+    output_dtype = _dtype_or_none(value_infos, var_output)
     if output_dtype is not None:
         assert dtype == output_dtype, 'tensor dtype unmatches storage dtype'
 
@@ -874,13 +827,13 @@ def Constant(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
 #    dtype = _np.dtype('float32') # HINT: force to float32
     shape = attrs.get('shape', None)  #
     if shape is None:
-        shape = _shape_or_none(value_infos, val_output)
+        shape = _shape_or_none(value_infos, var_output)
     if shape is None:
         shape = list(value.shape)
         _logger.warning(
             'in op (Constant -> %s): '
             'attribute "shape" of %s not inferred, '
-            'using value as 1-D tensor may lead to fails', outputs, val_output)
+            'using value as 1-D tensor may lead to fails', outputs, var_output)
 
     # generation
     value = value.tolist()
@@ -911,7 +864,7 @@ def Constant(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
         prog.Code('# {} = {} # passed directly as literal'.format(
             var_output, value))
 
-    value_infos[val_output]['const_value'] = value
+    value_infos[var_output]['const_value'] = value
 
 
 def ConstantOfShape(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
@@ -920,13 +873,12 @@ def ConstantOfShape(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
     """
 
     # I/O
-    val_shape, = inputs
-    val_output, = outputs
-    var_shape = _make_var_name(val_shape)
+    var_shape, = inputs
+    var_output, = outputs
 
-    shape = _const_weight_or_none(value_infos, val_shape)
+    shape = _const_weight_or_none(value_infos, var_shape)
     if shape is None:
-        shape = _shape_or_none(value_infos, val_output)
+        shape = _shape_or_none(value_infos, var_output)
     assert shape is not None, (
         'given shape is neither const value nor deductible from output, '
         'this is not supported')
@@ -959,53 +911,47 @@ def Conv(prog,
     """
 
     # I/O
-    val_x, val_w = inputs[:2]
-    val_y, = outputs
-    var_y = _make_var_name(val_y)
-
-    has_bias = len(inputs) == 3
-    if has_bias:
-        val_b, = inputs[2:]
+    var_x, var_w = inputs[:2]
+    var_y, var_b = (outputs + [None] * 1)[:2]
 
     # interpretation
     assert attrs.get(
         'auto_pad', 'NOTSET'
     ) == 'NOTSET', 'only auto_pad == NOTSET is supported'  # optional
-    kernel_shape = _shape(value_infos, val_w)[2:]  # OI...
+    kernel_shape = _shape(value_infos, var_w)[2:]  # OI...
     assert kernel_shape == attrs[
         'kernel_shape'], 'kernel_shape in attr unmatches value_info'  # HW
     convnd = len(kernel_shape)
     assert 2 <= convnd <= 3, 'only conv2d and conv3d is supported'
-    num_out_channels = _shape(value_infos, val_w)[0]  # OI...
+    num_out_channels = _shape(value_infos, var_w)[0]  # OI...
 
     fluid_op = 'conv{}d'.format(convnd)
     num_groups = attrs.get('group', 1)  # optional
     strides = attrs.get('strides', [1] * convnd)  # optional
     dilations = attrs.get('dilations', [1] * convnd)  # optional
     pads = attrs.get('pads', [0] * (convnd * 2))  # optional
-    paddings, val_x = _pad_if_asymmetric(prog, pads, val_x, value_infos)
-    var_x = _make_var_name(val_x)
+    paddings, var_x = _pad_if_asymmetric(prog, pads, var_x, value_infos)
     name_attr = ', name={}'.format(repr(name)) if name else ''
     if embed_params:
-        embed_params = (_check_embeddable(value_infos, val_w) and not has_bias
-                        or _check_embeddable(value_infos, val_b))
+        embed_params = (_check_embeddable(value_infos, var_w) and not var_b
+                        or _check_embeddable(value_infos, var_b))
         if not embed_params and name:
             _logger.warning('for op  %s(%s -> Conv -> %s)', name, inputs,
                             outputs)
             _logger.warning('broken Python code will be generated')
     if embed_params:
         assert name != ''
-        var_w = name + '.w_0'
-        value_infos[val_w]['embeded_as'].append(var_w)
-        if has_bias:
-            var_b = name + '.b_0'
-            value_infos[val_b]['embeded_as'].append(var_b)
+        embedded_w = name + '.w_0'
+        value_infos[var_w]['embedded_as'].append(embedded_w)
+        var_w = embedded_w
+        if var_b:
+            embedded_b = name + '.b_0'
+            value_infos[var_b]['embedded_as'].append(embedded_b)
+            var_b = embedded_b
             param_attr = ''
         else:
             param_attr = ', bias_attr=False'
     else:
-        var_w = _make_var_name(val_w)
-        var_b = _make_var_name(val_b) if has_bias else False
         param_attr = ', param_attr={}, bias_attr={}'.format(
             repr(var_w),
             repr(var_b) if var_b else False)
@@ -1036,7 +982,7 @@ def Conv(prog,
     prog.OpDesc(
         fluid_op,
         ([var_x, var_w], 'Input', 'Filter'),  # , 'Bias', 'ResidualData'
-        ([var_conv if has_bias else var_y], 'Output'),
+        ([var_conv if var_b else var_y], 'Output'),
         {
             'strides': strides,
             'paddings': paddings,
@@ -1044,13 +990,13 @@ def Conv(prog,
             'groups': num_groups,
         },
     )
-    if has_bias:
+    if var_b:
         prog.VarDesc(var_conv)
         prog.IntermediateOp(
             '',
             'Add',
             [var_conv, var_b],  #
-            [val_y],
+            [var_y],
             {'axis': 1},
             value_infos=value_infos,
             name=(name + '.bias'),
@@ -1073,13 +1019,8 @@ def ConvTranspose(prog,
     """
 
     # I/O
-    val_x, val_w = inputs[:2]
-    val_y, = outputs
-    var_y = _make_var_name(val_y)
-
-    has_bias = len(inputs) == 3
-    if has_bias:
-        val_b, = inputs[2:]
+    var_x, var_w = inputs[:2]
+    var_y, var_b = (outputs + [None] * 1)[:2]
 
     # interpretation
     assert attrs.get(
@@ -1088,41 +1029,40 @@ def ConvTranspose(prog,
     assert sum(attrs.get(
         'output_padding',
         [])) == 0, 'only zero output_padding is supported'  # optional ?
-    kernel_shape = _shape(value_infos, val_w)[2:]  # IO...
+    kernel_shape = _shape(value_infos, var_w)[2:]  # IO...
     assert kernel_shape == attrs[
         'kernel_shape'], 'kernel_shape in attr unmatches value_info'  # HW
     convnd = len(kernel_shape)
     assert 2 <= convnd <= 3, 'only conv2d_transpose and conv3d_transpose is supported'
-    num_out_channels = _shape(value_infos, val_w)[1]  # IO...
+    num_out_channels = _shape(value_infos, var_w)[1]  # IO...
 
     fluid_op = 'conv{}d_transpose'.format(convnd)
     num_groups = attrs.get('group', 1)  # optional
     strides = attrs.get('strides', [1] * convnd)  # optional
     dilations = attrs.get('dilations', [1] * convnd)  # optional
     pads = attrs.get('pads', [0] * (convnd * 2))  # optional
-    paddings, val_x = _pad_if_asymmetric(prog, pads, val_x, value_infos)
-    var_x = _make_var_name(val_x)
+    paddings, var_x = _pad_if_asymmetric(prog, pads, var_x, value_infos)
     name_attr = ', name={}'.format(repr(name)) if name else ''
     if embed_params:
-        embed_params = (_check_embeddable(value_infos, val_w) and not has_bias
-                        or _check_embeddable(value_infos, val_b))
+        embed_params = (_check_embeddable(value_infos, var_w) and not var_b
+                        or _check_embeddable(value_infos, var_b))
         if not embed_params and name:
             _logger.warning('for op  %s(%s -> ConvTranspose -> %s)', name,
                             inputs, outputs)
             _logger.warning('broken Python code will be generated')
     if embed_params:
         assert name != ''
-        var_w = name + '.w_0'
-        value_infos[val_w]['embeded_as'].append(var_w)
-        if has_bias:
-            var_b = name + '.b_0'
-            value_infos[val_b]['embeded_as'].append(var_b)
+        embedded_w = name + '.w_0'
+        value_infos[var_w]['embedded_as'].append(embedded_w)
+        var_w = embedded_w
+        if var_b:
+            embedded_b = name + '.b_0'
+            value_infos[var_b]['embedded_as'].append(embedded_b)
+            var_b = embedded_b
             param_attr = ''
         else:
             param_attr = ', bias_attr=False'
     else:
-        var_w = _make_var_name(val_w)
-        var_b = _make_var_name(val_b) if has_bias else False
         param_attr = ', param_attr={}, bias_attr={}'.format(
             repr(var_w),
             repr(var_b) if var_b else False)
@@ -1154,7 +1094,7 @@ def ConvTranspose(prog,
     prog.OpDesc(
         fluid_op,
         ([var_x, var_w], 'Input', 'Filter'),  # , 'Bias', 'ResidualData'
-        ([var_conv if has_bias else var_y], 'Output'),
+        ([var_conv if var_b else var_y], 'Output'),
         {
             'strides': strides,
             'paddings': paddings,
@@ -1163,13 +1103,13 @@ def ConvTranspose(prog,
             'groups': num_groups,
         },
     )
-    if has_bias:
+    if var_b:
         prog.VarDesc(var_conv)
         prog.IntermediateOp(
             '',
             'Add',
             [var_conv, var_b],  #
-            [val_y],
+            [var_y],
             {'axis': 1},
             value_infos=value_infos,
             name=(name + '.bias'),
@@ -1184,27 +1124,27 @@ def Gemm(prog, inputs, outputs, attrs, value_infos, name, *args, **kwargs):
     """
 
     # due to fluid fc don't support transposed weight, we use matmul + ew_add
-    val_a, val_b, val_c = inputs
-    val_y, = outputs
+    var_a, var_b, var_c = inputs
+    var_y, = outputs
 
     alpha = attrs.get('alpha', 1.)  # optional
     beta = attrs.get('beta', 1.)  # optional
     trans_a = bool(attrs.get('transA', 0))  # optional
     trans_b = bool(attrs.get('transB', 0))  # optional
 
-    val_mm = name + '_mm'  # explicit variable
+    var_mm = name + '_mm'  # explicit variable
     prog.Op(
         '',
         'MatMul',
-        [val_a, val_b],
-        [val_mm],  # val
+        [var_a, var_b],
+        [var_mm],  # val
         {
             'transpose_x': trans_a,
             'transpose_y': trans_b,
             'alpha': alpha,
         },
         value_infos=value_infos,
-        name=val_mm,
+        name=var_mm,
     )
     prog.op_descs[-1].attrs.extend(
         prog.OpDescAttrs({
@@ -1216,17 +1156,17 @@ def Gemm(prog, inputs, outputs, attrs, value_infos, name, *args, **kwargs):
             prog.Op(
                 '',
                 'Add',
-                [val_mm, val_c],
-                [val_y],  # val
+                [var_mm, var_c],
+                [var_y],  # val
                 {'axis': 1},
                 value_infos=value_infos,
                 name=(name + '_beta'),
             )
         else:
-            val_beta = name + '_beta'  # explicit variable
-            val_vm = name + '_vm'  # explicit variable
+            var_beta = name + '_beta'  # explicit variable
+            var_vm = name + '_vm'  # explicit variable
             if beta.is_integer():
-                vm_dtype = _dtype_or_none(value_infos, val_c)
+                vm_dtype = _dtype_or_none(value_infos, var_c)
                 if vm_dtype is None:
                     vm_dtype = _np.dtype('float32')
                     _logger.warning(
@@ -1239,16 +1179,16 @@ def Gemm(prog, inputs, outputs, attrs, value_infos, name, *args, **kwargs):
                 '',
                 'Constant',
                 [],
-                [val_beta],  # val
+                [var_beta],  # val
                 {'value': beta},
                 value_infos=value_infos,
-                name=val_beta,
+                name=var_beta,
             )
             prog.Op(
                 '',
                 'Mul',
-                [val_c, val_beta],
-                [val_vm],  # val
+                [var_c, var_beta],
+                [var_vm],  # val
                 dict(),
                 value_infos=value_infos,
                 name=(name + '_scale'),
@@ -1256,8 +1196,8 @@ def Gemm(prog, inputs, outputs, attrs, value_infos, name, *args, **kwargs):
             prog.Op(
                 '',
                 'Add',
-                [val_mm, val_vm],
-                [val_y],  # val
+                [var_mm, var_vm],
+                [var_y],  # val
                 {'axis': 1},
                 name=(name + '_bias'),
             )
@@ -1305,6 +1245,64 @@ def GlobalMaxPool(prog,
                         name=name)
 
 
+def GRU(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
+    """
+    onnx::GRU-7:
+    """
+
+    var_x, var_w, var_r, var_b, var_len, var_xh = (inputs + [None] * 3)[:6]
+    var_y, var_yh = (outputs + [None] * 2)[:2]
+
+    # interpretation
+    fluid_op = 'gru_unit'
+    param_attr = ''
+
+    # generation
+    prog.Code('{}, _, {} = layers.{}({}, {}, {}'
+              '{})'.format(
+                  var_yh,
+                  var_y,
+                  fluid_op,
+                  var_x,
+                  var_xh,
+                  0,
+                  param_attr,
+              ))
+
+
+#    raise NotImplementedError()
+
+
+def LSTM(prog, inputs, outputs, attrs, value_infos, name='', *args, **kwargs):
+    """
+    onnx::LSTM-7:
+    """
+
+    var_x, var_w, var_r, var_b, var_len, var_xh, var_xc, var_p = (
+        inputs + [None] * 5)[:8]
+    var_y, var_yh, var_yc = (outputs + [None] * 3)[:3]
+
+    # interpretation
+    fluid_op = 'lstm_unit'
+    param_attr = ''
+
+    # generation
+    prog.Code('{}, {}, {} = layers.{}({}, {}, {}'
+              '{})'.format(
+                  var_y,
+                  var_yh,
+                  var_yc,
+                  fluid_op,
+                  var_x,
+                  var_xh,
+                  var_xc,
+                  param_attr,
+              ))
+
+
+#    raise NotImplementedError()
+
+
 def MaxPool(prog, inputs, outputs, attrs, value_infos, name='', *args,
             **kwargs):
     """
@@ -1329,17 +1327,15 @@ def Pad(prog, inputs, outputs, attrs, value_infos, name='', *args, **kwargs):
     """
 
     # I/O
-    val_data, = inputs
-    val_output, = outputs
-    var_data = _make_var_name(val_data)
-    var_output = _make_var_name(val_output)
+    var_data, = inputs
+    var_output, = outputs
 
     # interpretation
     pads = attrs['pads']  # required
     mode = attrs.get('mode', 'constant')  # optional
     value = attrs.get('value', 0.)  # optional
-    data_shape = _shape_or_none(value_infos, val_data)
-    output_shape = _shape_or_none(value_infos, val_output)
+    data_shape = _shape_or_none(value_infos, var_data)
+    output_shape = _shape_or_none(value_infos, var_output)
     assume_pad2d = False
     if len(pads) == 4:
         assume_pad2d |= mode != 'constant'
@@ -1400,14 +1396,12 @@ def PRelu(prog,
     """
 
     # I/O
-    val_x, val_slope = inputs
-    val_y, = outputs
-    var_x = _make_var_name(val_x)
-    var_y = _make_var_name(val_y)
+    var_x, var_slope = inputs
+    var_y, = outputs
 
     # interpretation
     mode = 'channel'
-    slope_shape = _shape_or_none(value_infos, val_slope)
+    slope_shape = _shape_or_none(value_infos, var_slope)
     if slope_shape is not None:
         if len(slope_shape) == 0:
             mode = 'all'
@@ -1418,18 +1412,18 @@ def PRelu(prog,
     fluid_op = 'prelu'
     name_attr = ', name={}'.format(repr(name)) if name else ''
     if embed_params:
-        embed_params = _check_embeddable(value_infos, val_slope)
+        embed_params = _check_embeddable(value_infos, var_slope)
         if not embed_params and name:
             _logger.warning('for op  %s(%s -> PRelu -> %s)', name, inputs,
                             outputs)
             _logger.warning('broken Python code will be generated')
     if embed_params:
         assert name != ''
-        var_slope = name + '.w_0'
-        value_infos[val_slope]['embeded_as'].append(var_slope)
+        embedded_slope = name + '.w_0'
+        value_infos[var_slope]['embedded_as'].append(embedded_slope)
+        var_slope = embedded_slope
         param_attr = ''
     else:
-        var_slope = _make_var_name(val_slope)
         param_attr = ', param_attr={}'.format(repr(var_slope))
 
     # generation
@@ -1467,17 +1461,14 @@ def Reshape(prog, inputs, outputs, attrs, value_infos, name, *args, **kwargs):
     """
 
     # I/O
-    val_data, val_shape = inputs
-    val_reshaped, = outputs
-    var_data = _make_var_name(val_data)
-    var_shape = _make_var_name(val_shape)
-    var_reshaped = _make_var_name(val_reshaped)
+    var_data, var_shape = inputs
+    var_reshaped, = outputs
 
     # interpretation
-    shape = _const_weight_or_none(value_infos, val_shape)
-    is_const_shape = shape and 'const_value' in value_infos[val_shape]
+    shape = _const_weight_or_none(value_infos, var_shape)
+    is_const_shape = shape and 'const_value' in value_infos[var_shape]
     if shape is None:
-        shape = _shape_or_none(value_infos, val_reshaped)
+        shape = _shape_or_none(value_infos, var_reshaped)
 
 
 #    assert shape is not None, ('given shape is neither const value nor deductible from output, '
@@ -1493,8 +1484,7 @@ def Reshape(prog, inputs, outputs, attrs, value_infos, name, *args, **kwargs):
     name_attr = ', name={}'.format(repr(name)) if name else ''
 
     # generation
-    val_shape_int32 = val_shape + '_int32'  # explicit variable
-    var_shape_int32 = _make_var_name(val_shape_int32)
+    var_shape_int32 = var_shape + '_int32'  # explicit variable
     prog.Code('# shape:{}={} # const as literal'.format(var_shape, shape))
     if is_const_shape:
         prog.Code('{} = layers.{}({}'
@@ -1511,8 +1501,8 @@ def Reshape(prog, inputs, outputs, attrs, value_infos, name, *args, **kwargs):
         prog.Op(
             '',
             'Cast',
-            [val_shape],
-            [val_shape_int32],  # var
+            [var_shape],
+            [var_shape_int32],  # var
             {'to': _np.dtype('int32')},  # use np.dtype
             value_infos=value_infos,
             name=(name + '_cast'),
@@ -1595,17 +1585,15 @@ def Slice(prog, inputs, outputs, attrs, value_infos, *args, **kwargs):
     """
 
     # I/O
-    val_data, = inputs
-    val_output, = outputs
-    var_data = _make_var_name(val_data)
-    var_output = _make_var_name(val_output)
+    var_data, = inputs
+    var_output, = outputs
 
     # interpretation
     fluid_op = 'slice'
     axes = attrs['axes']  # required
     starts = attrs['starts']  # required
     ends = attrs['ends']  # required
-    shape = _shape_or_none(value_infos, val_data)
+    shape = _shape_or_none(value_infos, var_data)
     if shape is not None:
         #        ndims = len(shape)
         #        for idx, value in enumerate(axes):
@@ -1654,9 +1642,7 @@ def Split(prog, inputs, outputs, attrs, *args, name='', **kwargs):
     """
 
     # I/O
-    val_input, = inputs
-    var_outs = [_make_var_name(val) for val in outputs]
-    var_input = _make_var_name(val_input)
+    var_input, = inputs
 
     # interpretation
     fluid_op = 'split'
@@ -1668,7 +1654,7 @@ def Split(prog, inputs, outputs, attrs, *args, name='', **kwargs):
     prog.Code('{} = layers.{}({}, {}'
               ', dim={}'
               '{})'.format(
-                  ', '.join(var_outs),
+                  ', '.join(outputs),
                   fluid_op,
                   var_input,
                   split,
@@ -1676,12 +1662,12 @@ def Split(prog, inputs, outputs, attrs, *args, name='', **kwargs):
                   axis,
                   name_attr,
               ))
-    for var_out in var_outs:
+    for var_out in outputs:
         prog.VarDesc(var_out)
     prog.OpDesc(
         fluid_op,
         (var_input, 'X'),
-        ([var_outs], *(['Out'] * len(var_outs))),
+        ([outputs], *(['Out'] * len(outputs))),
         {
             'axis': axis,
             'sections': split,
@@ -1695,9 +1681,7 @@ def Sum(prog, inputs, outputs, *args, **kwargs):
     """
 
     # I/O
-    val_sum, = outputs
-    var_inps = [_make_var_name(val) for val in inputs]
-    var_sum = _make_var_name(val_sum)
+    var_sum, = outputs
 
     # interpretation
     fluid_op = 'sums'
@@ -1706,14 +1690,14 @@ def Sum(prog, inputs, outputs, *args, **kwargs):
     prog.Code('{} = layers.{}({})'.format(
         var_sum,
         fluid_op,
-        '[' + ', '.join(var_inps) + ']',
+        '[' + ', '.join(inputs) + ']',
         # attrs
     ))
     fluid_op = 'sum'
     prog.VarDesc(var_sum)
     prog.OpDesc(
         fluid_op,
-        (var_inps, *(['X'] * len(var_inps))),
+        (inputs, *(['X'] * len(inputs))),
         ([var_sum], 'Out'),
         dict(),
     )
@@ -1725,14 +1709,11 @@ def Tile(prog, inputs, outputs, attrs, value_infos, name='', *args, **kwargs):
     """
 
     # I/O
-    val_input, val_repeats = inputs
-    val_output, = outputs
-    var_input = _make_var_name(val_input)
-    var_repeats = _make_var_name(val_repeats)
-    var_output = _make_var_name(val_output)
+    var_input, var_repeats = inputs
+    var_output, = outputs
 
     # interpretation
-    repeats = _const_weight_or_none(value_infos, val_repeats)
+    repeats = _const_weight_or_none(value_infos, var_repeats)
     assert repeats is not None, 'only const repeats is supported'
     fluid_op = 'expand'
     name_attr = ', name={}'.format(repr(name)) if name else ''
@@ -1764,10 +1745,8 @@ def Transpose(prog, inputs, outputs, attrs, *args, name='', **kwargs):
     """
 
     # I/O
-    val_data, = inputs
-    val_transposed, = outputs
-    var_data = _make_var_name(val_data)
-    var_transposed = _make_var_name(val_transposed)
+    var_data, = inputs
+    var_transposed, = outputs
 
     # interpretation
     fluid_op = 'transpose'
diff --git a/onnx2fluid/onnx2fluid/torch_export_helper.py b/onnx2fluid/onnx2fluid/torch_export_helper.py
index 39f034317c76b3372c3a969df33dc20fe264ddaf..dfb1ea0719a75657b5ac89343a6261d6e6b9e814 100644
--- a/onnx2fluid/onnx2fluid/torch_export_helper.py
+++ b/onnx2fluid/onnx2fluid/torch_export_helper.py
@@ -6,6 +6,9 @@ Created on Fri Mar 22 11:22:46 2019
 @author: Macrobull
 """
 
+from __future__ import division
+
+import logging
 import numpy as np
 import torch
 
@@ -24,6 +27,8 @@ from typing import (
     Union,
 )
 
+logger = logging.getLogger(__name__)
+
 __all__ = [
     'export_data',
     'export_onnx_with_validation',
@@ -76,7 +81,7 @@ def export_data(state_dict: Mapping[Text, Any], prefix: Text = '') -> None:
         return str(obj)
 
     prefix_ = prefix + ('_' if prefix else '')
-    fp = open('{}.txt'.format(prefix or 'meta'), 'w')
+    fp = open('{}.txt'.format(prefix or 'meta'), mode='w')
     for key, value in state_dict.items():
         data = None
         if torch.is_tensor(value):
@@ -93,7 +98,7 @@ def export_data(state_dict: Mapping[Text, Any], prefix: Text = '') -> None:
 
 
 def export_onnx_with_validation(
-        model: torch.nn.Module,
+        model: torch.nn.Module,  # or JITScriptModule
         inputs: Sequence[Union[torch.Tensor, Sequence[object]]],
         export_basepath: Text,
         input_names: Optional[List[Text]] = None,
diff --git a/onnx2fluid/onnx2fluid/validation.py b/onnx2fluid/onnx2fluid/validation.py
index 22e78d9e604568931d9077802d37682ae4b7c6ae..4374c7eb448fddafbf1514657545c30acefbeaa5 100644
--- a/onnx2fluid/onnx2fluid/validation.py
+++ b/onnx2fluid/onnx2fluid/validation.py
@@ -43,7 +43,8 @@ def fluid_prog_shape_infer(prog):
 
     import paddle.fluid as fluid
 
-    assert isinstance(prog, fluid.framework.Program)
+    assert isinstance(prog,
+                      fluid.framework.Program), 'prog is not a Program instance'
 
     logger.info('performing type-shape inference ...')
     for block in prog.blocks:
@@ -84,6 +85,8 @@ def validate(fluid_model_filename,
     inference the converted Paddle fluid model, validate with given golden data
     """
 
+    assert isinstance(fluid_model_filename, str)
+
     import numpy as np
     import paddle.fluid as fluid
 
@@ -153,7 +156,7 @@ def validate(fluid_model_filename,
         input_data = flatten_dict(input_data)
         output_data = flatten_dict(output_data)
         input_names = input_data.keys()
-        output_names = output_data.keys()
+        #        output_names = output_data.keys()
         logger.info('with %d inputs and %d outputs', len(input_data),
                     len(output_data))
     else:
diff --git a/onnx2fluid/onnx2fluid/writer.py b/onnx2fluid/onnx2fluid/writer.py
index 70bd72765e067538230c5e5644d994af8d902099..9d8ba4b7990b2bf0e9357afd3a1583943ed64e6b 100644
--- a/onnx2fluid/onnx2fluid/writer.py
+++ b/onnx2fluid/onnx2fluid/writer.py
@@ -16,7 +16,6 @@ from collections import OrderedDict as Dict
 logger = logging.getLogger(__name__)
 
 from . import symbolic
-from .symbolic import _make_var_name as make_var_name
 
 try:
     import paddle.fluid.proto.framework_pb2 as framework_pb2
@@ -63,7 +62,7 @@ def make_attr_name(name):
 
     assert name != '', 'name should not be empty'
 
-    for s in ' \\|/:-':  #
+    for s in ' \\|/:.-':  #
         name = name.replace(s, '_')
     if not name.startswith('_'):
         name = '_' + name
@@ -207,7 +206,7 @@ class Program(object):
         return desc
 
     def VarDesc(self,
-                var_name,
+                name,
                 persistable=False,
                 value_info=None,
                 remove_batch=None):
@@ -215,18 +214,16 @@ class Program(object):
         add VarDesc,
         """
 
-        assert var_name not in self.var_descs, 'var naming conflicted'
+        assert name not in self.var_descs, 'var naming conflicted'
 
         var_desc = framework_pb2.VarDesc()
-        var_desc.name = var_name
+        var_desc.name = name
         var_desc.persistable = persistable
         var_desc.type.type = framework_pb2.VarType.LOD_TENSOR
-        self.var_descs[var_name] = var_desc
+        self.var_descs[name] = var_desc
 
         if value_info:
-            self.VarTypeShapeInfo(var_name,
-                                  value_info,
-                                  remove_batch=remove_batch)
+            self.VarTypeShapeInfo(name, value_info, remove_batch=remove_batch)
 
     def Op(self, domain, op_type, *args, **kwargs):
         """
@@ -260,19 +257,19 @@ class Program(object):
         else:
             self.code_mutable = code_mutable
 
-    def VarTypeShapeInfo(self, var_name, value_info, remove_batch=None):
+    def VarTypeShapeInfo(self, name, value_info, remove_batch=None):
         """
         set value_info for var
         """
 
-        if var_name not in self.var_descs:
+        if name not in self.var_descs:
             return
 
         dtype = value_info.get('dtype', None)
         if dtype is None:
             return
 
-        var_desc = self.var_descs[var_name]
+        var_desc = self.var_descs[name]
         tensor_desc = var_desc.type.lod_tensor.tensor
         tensor_desc.data_type = self.Dtype(dtype)  # required
 
@@ -292,8 +289,7 @@ class Writer(object):
     fluid code and desc writter
     """
 
-    #	CODE_INDENT = ' ' * 4
-    CODE_INDENT = '\t'
+    CODE_INDENT = ' ' * 4  # '\t'
 
     @staticmethod
     def header_code(func_name, info=''):
@@ -313,6 +309,7 @@ class Writer(object):
         codes.append('from paddle.fluid import initializer, layers')
         codes.append('')
         codes.append('')
+
         codes.append('def {}():'.format(func_name))
         return codes
 
@@ -342,24 +339,26 @@ class Writer(object):
         emit an ONNX weight into program
         """
 
-        if value_info.get('embeded_as', []):
-            var_names = value_info['embeded_as']
-            prog.Code('# parameter {} embeded as {}'.format(name, var_names))
-            for var_name in var_names:
-                prog.VarDesc(var_name, persistable=True, value_info=value_info)
+        if value_info.get('embedded_as', []):
+            embedded_names = value_info['embedded_as']
+            prog.Code('# parameter {} embedded as {}'.format(
+                name, embedded_names))
+            for embedded_name in embedded_names:
+                prog.VarDesc(embedded_name,
+                             persistable=True,
+                             value_info=value_info)
         else:
-            var_name = make_var_name(name)
             attr_name = make_attr_name(name)
-            prog.Code('# parameter {}: {}'.format(name, var_name))
+            prog.Code('# parameter {}'.format(name))
             prog.Code('{} = ParamAttr(name={})'  # , trainable=True
-                      .format(attr_name, repr(var_name)))
+                      .format(attr_name, repr(name)))
             prog.Code(
                 '{} = layers.create_parameter(shape={}, dtype={}, name={}, attr={}'
                 ', default_initializer=initializer.Constant(0))'  #, is_bias={}
-                .format(var_name, value_info['shape'],
+                .format(name, value_info['shape'],
                         repr(value_info['dtype'].name), repr(name),
                         attr_name))  #, value_info.get('is_bias', False)))
-            prog.VarDesc(var_name, persistable=True, value_info=value_info)
+            prog.VarDesc(name, persistable=True, value_info=value_info)
 
     @staticmethod
     def emit_inputs(prog, names, value_infos, remove_batch=None):
@@ -368,7 +367,6 @@ class Writer(object):
         """
 
         for idx, name in enumerate(names):
-            var_name = make_var_name(name)
             value_info = value_infos[name]
             shape = value_info['shape']
             if remove_batch is None:
@@ -377,13 +375,13 @@ class Writer(object):
             if remove_batch:
                 shape = shape[1:]
 
-            prog.Code('# input {}: {}'.format(name, var_name))
+            prog.Code('# input {}'.format(name))
             prog.Code((
                 '{} = layers.data(name={}, shape={}, dtype={}, '
                 'append_batch_size={})'  # , stop_gradient=True
             ).format(
-                var_name,
-                repr(var_name),
+                name,
+                repr(name),
                 shape,
                 repr(value_info['dtype'].name),
                 remove_batch,
@@ -391,12 +389,10 @@ class Writer(object):
             prog.OpDesc(
                 'feed',
                 (['feed'], 'X'),
-                ([var_name], 'Out'),
+                ([name], 'Out'),
                 {'col': idx},
             )
-            prog.VarDesc(var_name,
-                         value_info=value_info,
-                         remove_batch=remove_batch)
+            prog.VarDesc(name, value_info=value_info, remove_batch=remove_batch)
 
     @staticmethod
     def emit_outputs(prog, names):  #, value_infos
@@ -406,12 +402,11 @@ class Writer(object):
 
         code = 'return '
         for idx, name in enumerate(names):
-            var_name = make_var_name(name)
-            code += var_name + ', '
+            code += name + ', '
 
             prog.OpDesc(
                 'fetch',
-                ([var_name], 'X'),
+                ([name], 'X'),
                 (['fetch'], 'Out'),
                 {'col': idx},
             )
@@ -458,8 +453,7 @@ class Writer(object):
         for name, weight in weights.items():
             assert isinstance(weights, dict), 'dict type weights required'
 
-            var_name = make_var_name(name)
-            filename = os.path.join(save_dir, var_name)
+            filename = os.path.join(save_dir, name)
             Writer.write_weight(weight, filename)
             logger.debug('saved weight %s to %s', name, filename)
 
diff --git a/onnx2fluid/requirements.txt b/onnx2fluid/requirements.txt
index 4d57359977be2d7106553ccd703132ef2691a3e4..9a67fa83216ba09789469855e2bcca199d8a617c 100644
--- a/onnx2fluid/requirements.txt
+++ b/onnx2fluid/requirements.txt
@@ -1,3 +1,3 @@
 -e .
 onnx>=1.4
-paddlepaddle
+paddlepaddle>=1.5