http://python3porting.com/cextensions.html

gistfile1.c

/* pyuv.h */
#if PY_VERSION_HEX >= 0x03000000
#define PY3
#define PyInt_FromSsize_t PyLong_FromSsize_t
#define PyInt_FromLong PyLong_FromLong

/* pending start */
#define PyString_FromString PyBytes_FromString
#define PyString_AsString PyBytes_AsString
#define PyString_FromStringAndSize PyBytes_FromStringAndSize
#define PyString_Check PyBytes_Check
#define PyString_Size PyBytes_Size
/* PyDict_SetItemString ? */
/* pending end */
#endif

/* pyuv.c */

#ifdef PY3
/* pyuv_module */
static PyModuleDef pyuv_module = {
    PyModuleDef_HEAD_INIT,
    "pyuv",                                   /*m_name*/
    NULL,                                     /*m_doc*/
    -1,                                       /*m_size*/
    NULL,                                     /*m_methods*/
};
#endif

    /* Main module */
    PyObject *pyuv;
#ifdef PY3
    pyuv = PyModule_Create(&pyev_module);
#else
    pyuv = Py_InitModule("pyuv", NULL);
#endif

#if PY_MAJOR_VERSION < 3
    PyMODINIT_FUNC
    init_errno(void)
    {
        moduleinit();
    }
#else
    PyMODINIT_FUNC
    PyInit__errno(void)
    {
        return moduleinit();
    }
#endif