code: func supervisor(paths chan string, bundler chan *x509.Certificate, numWorkers int) {
  	var workerPool sync.WaitGroup
  	for i := 0; i < numWorkers; i++ {
  		workerPool.Add(1)
  		go worker(paths, bundler, &workerPool)
  	}
  	workerPool.Wait()
  	close(bundler)
  }
docs: // supervisor sets up the workers and signals the bundler that all
  // certificates have been processed.