go.c

#include <stdio.h>

void foo() {
    printf("Hello world\n");
}

int bar() {
    return 1;
}

int baz(int n) {
    int sum = 0;
    for (int i = 0; i < n; i++) {
        sum += i;
    }
    return sum;
}

go.py

import ctypes

libgo = ctypes.cdll.LoadLibrary('./libgo.so')
libgo.foo()
print(libgo.bar())
print(libgo.baz(100))

Makefile

all: go.so

go.o: go.c
	gcc -std=c99 -c -fPIC go.c -o go.o

go.so: go.o
	gcc -shared -Wl,-soname,libgo.so -o libgo.so go.o