func New(errorThreshold, successThreshold int, timeout time.Duration) *Breaker
New constructs a new circuit-breaker that starts closed. From closed, the breaker opens if "errorThreshold" errors are seen without an error-free period of at least "timeout". From open, the breaker half-closes after "timeout". From half-open, the breaker closes after "successThreshold" consecutive successes, or opens on a single error.