func withBackoff(bf backoffFunc) retryOption {
	return retryOption{applyFunc: func(o *options) {
		o.backoffFunc = bf
	}}
}
func withBackoff(bf backoffFunc) retryOption {
	return retryOption{applyFunc: func(o *options) {
		o.backoffFunc = bf
	}}
}
func withBackoff ( bf backoffFunc ) retryOption { return retryOption { applyFunc : func ( o * options ) { o . backoffFunc = bf } } }
// WithBackoff sets the `BackoffFunc `used to control time between retries.
WithBackoff sets the BackoffFunc used to control time between retries .