pub trait TitleDataExt {
// Required methods
fn get_cnmts(
&mut self,
keyset: &Keyset,
title_keyset: Option<&TitleKeys>,
) -> Result<Vec<Cnmt>, Error>;
fn title_id(&self) -> Result<u64, Error>;
// Provided method
fn title_id_serialized(&self) -> Result<String, Error> { ... }
}