pub trait L4Fetch: Send + Sync {
// Required method
fn fetch<'life0, 'life1, 'life2, 'async_trait>(
&'life0 self,
l4: L4Conn,
conn: &'life1 Arc<ConnContext>,
ctx: &'life2 mut FlowCtx,
) -> Pin<Box<dyn Future<Output = Result<Tunnel, Error>> + Send + 'async_trait>>
where Self: 'async_trait,
'life0: 'async_trait,
'life1: 'async_trait,
'life2: 'async_trait;
}