区块链技术概括起来是指通过去中心化和去信任的方式集体维护一个可靠数据库的技术。其实，区块链技术并不是一种单一的、全新的技术，
而是多种现有技术整合的结果，这些技术与数据库巧妙地组合在一起，形成了一种新的数据记录、传递、存储与呈现的方式
def export_model_from_pytorch_to_onnx(pytorch_model,onnx_model_name):
batch_size=1
#input to the model
x=torch.randn(batch_size,1,32,32)
out=pytorch_model(x)
#print("out:",out)
#export the model
torch.onnx.export(pytorch_model,#model being run
x,#model input(or a tuple for multiple inputs)
onnx_model_name,#where to save the model(can be a file or file-like object)
export_params=True,#store the trained parameter weights inside the model file
opset_version=9,#the ONNX version to export the model to
do_constant_folding=True,#whether to execute constant folding for optimization
input_names=['input'],#the model's input names
output_names=['output'],#the model's output names
dynamic_axes={'input':{0:'batch_size'},#variable length axes
'output':{0:'batch_size'}})
def verify_onnx_model(onnx_model_name):
#model is an in-memory ModelProto
model=onnx.load(onnx_model_name)
#print("the model is:n{}".format(model))
#check the model
try:
onnx.checker.check_model(model)
except onnx.checker.ValidationError as e:
print("the model is invalid:%s"%e)
exit(1)
else:
print("the model is valid")
