// and not continuously try to update.
	// Should not be combined with ReturnLastGood.
	CacheError bool

	// If NoWait is set, Get() will return the last good value,
	// if TTL has expired but 2x TTL has not yet passed,
	// but will fetch a new value in the background.
	NoWait bool
}

// Cache contains a synchronized value that is considered valid
// for a specific amount of time.