static int
_sharednsitem_init(struct _sharednsitem *item, PyObject *key, PyObject *value)
{
    item->name = _copy_raw_string(key);

...

static char *
_copy_raw_string(PyObject *strobj)
{
    const char *str = PyUnicode_AsUTF8(strobj);
    if (str == NULL) {
        return NULL;
    }
    char *copied = PyMem_Malloc(strlen(str)+1);
    if (copied == NULL) {
        PyErr_NoMemory();
        return NULL;
    }
    strcpy(copied, str);
    return copied;
}

_sharedns *result_shread = _sharedns_new(1);


#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
    // Switch to interpreter.
    PyThreadState *new_tstate = PyInterpreterState_ThreadHead(interp);
    PyThreadState *save1 = PyEval_SaveThread();

    (void)PyThreadState_Swap(new_tstate);
#else
    // Switch to interpreter.
    PyThreadState *save_tstate = NULL;
    if (interp != PyInterpreterState_Get()) {
        // XXX Using the "head" thread isn't strictly correct.
        PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
        // XXX Possible GILState issues?
        save_tstate = PyThreadState_Swap(tstate);
    }
#endif
    
    PyObject *module = PyImport_ImportModule(PyUnicode_AsUTF8(module_name));
    PyObject *function = PyObject_GetAttr(module, function_name);
    
    result = PyObject_Call(function, args, kwargs);

    if (result == NULL) {
        // exception handler
        ...
    }

    if (result && _sharednsitem_init(&result_shread->items[0], PyUnicode_FromString("result"), result) != 0) {
        PyErr_Format(RunFailedError, "interp_call_function result convert to shared failed");
        return NULL;;
    }
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
    // Switch back.
    PyEval_RestoreThread(save1);
#else
    // Switch back.
    if (save_tstate != NULL) {
        PyThreadState_Swap(save_tstate);
    }
#endif
    // ...

    if (result) {
        result = _PyCrossInterpreterData_NewObject(&result_shread->items[0].data);
        _sharedns_free(result_shread);
    }