pip install pybind11

g++ -O3 -DNDEBUG -Wall -Wextra -shared -std=c++17 -fPIC $(python3 -m pybind11 --includes) mandel.cpp -o mandel$(python3-config --extension-suffix)


see https://stackoverflow.com/questions/44659924/returning-numpy-arrays-via-pybind11
for how to construct the array we are going to return in the subroutine itself.