in src/lib.rs [407:418]
fn on_checkpoint(&mut self, deadline: Instant) -> Result<(), RuntimeError> {
let current_time = Instant::now();
if current_time >= deadline {
return Err(RuntimeError::Timeout);
}
self.trace_progress();
self.set_next_checkpoint(deadline, current_time);
self.completed_iter += 1;
Ok(())
}