calling c++ functions in python: undefined symbol: TF_DeleteTensor

Question

I want to do inference of a python classification model (tensorflow framework) in c++ (in order to increase speed). I succeeded to do that using cppflow. The next step is to call the inference c++ function in python in order to use it in my application. Here is the c++ script predict.cpp:

#include <iostream>
#include "cppflow/cppflow.h"
#include <string>

using namespace std;


extern "C" cppflow::tensor predict(string model_path, string img_path) {

    cppflow::model model(model_path);
    auto input = cppflow::decode_jpeg(cppflow::read_file(string(img_path)));
    
    input = cppflow::cast(input, TF_UINT8, TF_FLOAT);
    input = cppflow::expand_dims(input, 0);
    
    auto output = model({{"serving_default_input_2:0", input}},{"StatefulPartitionedCall:0"});
    
    auto res = output[0];
    return res;

}

I followed this site in order to call the "predict" function in python, I constructed "predict.so" using the following command line: g++ -I../cppflow/include/ -fPIC -shared -o predict.so predict.cpp Then I wrote the following python script:

from ctypes import *
model_path = 'xxx'
image_path = 'yyy'
so_file = "./predict.so"
my_functions = CDLL(so_file)
result = my_functions.predict(model_path, image_path)

However, I got the following error when running "my_functions = CDLL(so_file)":

OSError: undefined symbol: TF_DeleteTensor

Anybody knows why? I also tried to use boost library, but I didn't manage to run it properly. If you can show me how to use it properly I would be very grateful. Thank you very much!!