pub trait LightningBuilder {
// Required method
fn build<'life0, 'async_trait>(
&'life0 self,
runtime: Arc<Runtime>,
) -> Pin<Box<dyn Future<Output = Box<dyn ILnRpcClient>> + Send + 'async_trait>>
where Self: 'async_trait,
'life0: 'async_trait;
// Provided method
fn lightning_mode(&self) -> Option<LightningMode> { ... }
}