pub trait BuildableImplExt: Sealed + ObjectSubclass {
    // Provided methods
    fn parent_set_id(&self, id: &str) { ... }
    fn parent_id(&self) -> Option<GString> { ... }
    fn parent_add_child(
        &self,
        builder: &Builder,
        child: &Object,
        type_: Option<&str>
    ) { ... }
    fn parent_set_buildable_property(
        &self,
        builder: &Builder,
        name: &str,
        value: &Value
    ) { ... }
    fn parent_parser_finished(&self, builder: &Builder) { ... }
    fn parent_internal_child(
        &self,
        builder: &Builder,
        name: &str
    ) -> Option<Object> { ... }
    fn parent_construct_child(&self, builder: &Builder, name: &str) -> Object { ... }
}