Saving map<string, map<string, torch::Tensor>> objects in LibTorch

My use case in LibTorch is as follows. I have a map<string, map<string, torch::Tensor>>
object in C++ that I would like to serialize for FAST reading for a torch::data::Dataset<> subclass.

Supposing I write a function

# include <torch/torch.h>

using namespace std;

void save_serialized_obj(map<string, map<string, torch::Tensor>>, string save_fp) {
      

} 

map<string, map<string, torch::Tensor>> load_serialized_obj(string save_fp) {


}

What is the easiest/fastest way to achieve this functionality?