pub unsafe extern "C" fn jsc_class_add_constructor(
    jsc_class: *mut JSCClass,
    name: *const c_char,
    callback: GCallback,
    user_data: gpointer,
    destroy_notify: GDestroyNotify,
    return_type: GType,
    n_params: c_uint,
     ...
) -> *mut JSCValue