Function PyDict_SetDefaultRef 

pub unsafe extern "C" fn PyDict_SetDefaultRef(
    mp: *mut PyObject,
    key: *mut PyObject,
    default_value: *mut PyObject,
    result: *mut *mut PyObject,
) -> c_int

Available on Py_3_13 and (Py_3_15 or non-Py_LIMITED_API) only.