code: func NewRetryingSink(sink Sink, strategy RetryStrategy) *RetryingSink {
  	rs := &RetryingSink{
  		sink:     sink,
  		strategy: strategy,
  		closed:   make(chan struct{}),
  	}
  
  	return rs
  }
docs: // NewRetryingSink returns a sink that will retry writes to a sink, backing
  // off on failure. Parameters threshold and backoff adjust the behavior of the
  // circuit breaker.