Creating spamtuple instead of spamlist from CPython's xxsubtype.c example template

Question

While in the process of learning the C API for CPython I wanted to modify the xxsubtype.c template example that contains spamlist and spamdict to create spamtuple. The does not work directly, I believe, since tuples are immutable and so you cannot use tp_init. I believe that you have to use tp_new. The goal is to have the following python code work:

import xxsubtype
s = xxsubstype.spamtuple((1,2,3))

What I have done so far is change spamlist to spamtuple; change Py_List_Type to Py_Tuple_Type etc and then add a spamtuple_new:

static PyObject *
spamtuple_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    spamtupleobject *self;

    self = (spamtupleobject *)PyTuple_Type.tp_new(type, args, kwds);
    if (self != NULL) {
        self->state = 0;  // Initialize custom attributes
    }
    return (PyObject *)self;
}

Then update spamtuple_type with

static PyTypeObject spamtuple_type = {
    PyVarObject_HEAD_INIT(DEFERRED_ADDRESS(&PyType_Type), 0)
    "xxsubtype.spamtuple",
    sizeof(spamtupleobject),
    0,
    0,                                          /* tp_dealloc */
 ...
    (initproc)spamtuple_init,                    /* tp_init */
    0,                                          /* tp_alloc */
    spamtuple_new,                              /* tp_new */
};

When I load the module up in python and attempt

s = xxsubstype.spamtuple((1,2,3))

I get a seg fault. Looking for help in general how to accept tuples as arguments. Eventually I would like to be able to do:

s = xxsubtype.spamtuple((1,2,3), data=data)

where data is a tuple or reference to a class. Any help would be appreciated.