pub trait ExtraFor<T> {
// Required method
fn parse(&self, data: &[u8], resolve: &Arc<dyn Resolve>) -> Result<T>;
// Provided method
fn parse_checked(
&self,
hash: Hash,
data: &[u8],
resolve: &Arc<dyn Resolve>,
) -> Result<T>
where T: FullHash { ... }
}