newAuthToken func(audience string) string

	sync.RWMutex // mutex for lastErr
	lastErr      error
	lastErrTime  time.Time
}

type restError string

func (e restError) Error() string {
	return string(e)
}

func (e restError) Timeout() bool {
	return true
}

// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
// return true if the string includes a port.