static PyObject* py_inc_array(PyObject* self, PyObject* args) {
    PyObject *obj = NULL;
    double inc = 0.0;
    if (!PyArg_ParseTuple(args, "Od", &obj, &inc))
        return NULL;

    PyArrayObject *arr = (PyArrayObject *)PyArray_FROM_OTF(obj, NPY_DOUBLE, NPY_ARRAY_IN_ARRAY);
    if (arr == NULL)
        return NULL;

    inc_array(arr, inc);
    Py_DECREF(arr);
    Py_RETURN_NONE;
}