Macro hedge 

macro_rules! hedge {
    ($delay:expr, $primary:expr, $backup:expr) => { ... };
}

Macro for hedging an operation (placeholder).

In the full implementation, this spawns the primary, waits for the deadline, and races with the backup if needed.

Example (API shape)

let result = hedge!(
    100.millis(),           // hedge delay
    call_primary_server(),  // primary future
    || call_backup_server() // backup closure (only called if needed)
);