int
PyUnicodeEncodeError_GetStart(PyObject *exc, Py_ssize_t *start)
{
    Py_ssize_t size;
    PyObject *obj = get_unicode(((PyUnicodeErrorObject *)exc)->object,
                                "object");
    if (!obj)
        return -1;
    *start = ((PyUnicodeErrorObject *)exc)->start;
    size = PyUnicode_GET_LENGTH(obj);
    if (*start<0)
        *start = 0; /*XXX check for values <0*/
    if (*start>=size)
        *start = size-1;
    Py_DECREF(obj);
    return 0;
}