working example of this idea is in ctypes_and_api

casting_pointer/main

casting_pointer/main.c

ctypes/compile.sh

ctypes/main.py

ctypes/mean.c

ctypes/mean.h

ctypes_and_api/__pycache__/functions.cpython-36.pyc

ctypes_and_api/compile_shared_lib.sh

ctypes_and_api/demolib.c

ctypes_and_api/demolib.h

ctypes_and_api/demomodule.c

ctypes_and_api/functions.py

ctypes_and_api/libmean.so.1

ctypes_and_api/main.py

ctypes_and_api/mean.c

ctypes_and_api/mean.h

ctypes_and_api/readme.org

ctypes_and_api/setup.py

python-c-api_solution/demolib.o

python-c-api_solution/main.c