python c extension

#include <Python.h>

// source: https://stackoverflow.com/questions/8001923/python-extension-module-with-variable-number-of-arguments
// source: https://codedamn.com/news/python/implementing-custom-python-c-extensions-step-by-step-guide

static PyObject* compute_linear_index(PyObject* self, PyObject* args) {
    Py_ssize_t order = PyTuple_Size(args) / 2;
    Py_ssize_t i;
    unsigned int *dimensions;
    unsigned int *index;
    long p = 1;
    long final = 0;

    dimensions = malloc(order*sizeof(unsigned int));
    for(i = 0; i < order; i++) {
        dimensions[i] = PyLong_AsUnsignedLong(PyTuple_GetItem(args, i));
    }

    index = malloc(order*sizeof(unsigned int));
    for(i = 0; i < order; i++) {
        index[i] = PyLong_AsUnsignedLong(PyTuple_GetItem(args, i+order));
    };

    for(i = 0; i < order; i++) {
        final += index[order-i-1]*p;
        p *= dimensions[order-i-1];
    }

    free(dimensions);
    free(index);

    return PyLong_FromLong(final);
}

static PyMethodDef TensorMethods[] = {
    {"compute_linear_index", compute_linear_index, METH_VARARGS, "Compute linear index."},
    {NULL, NULL, 0, NULL} /* Sentinel */
};

static struct PyModuleDef tensor_module = {
    PyModuleDef_HEAD_INIT,
    "tensor", /* name of module */
    NULL,           /* module documentation, may be NULL */
    -1,             /* size of per-interpreter state of the module, or -1 if the module keeps state in global variables. */
    TensorMethods
};

PyMODINIT_FUNC PyInit_tensor(void) {
    return PyModule_Create(&tensor_module);
}