code: func (b *BulkIndexer) Start() {
  	b.shutdownChan = make(chan chan struct{})
  
  	go func() {
  		// XXX(j): Refactor this stuff to use an interface.
  		if b.Sender == nil {
  			b.Sender = b.Send
  		}
  		// Backwards compatibility
  		b.startHttpSender()
  		b.startDocChannel()
  		b.startTimer()
  		ch := <-b.shutdownChan
  		time.Sleep(2 * time.Millisecond)
  		b.Flush()
  		b.shutdown()
  		ch <- struct{}{}
  	}()
  }
docs: // Starts this bulk Indexer running, this Run opens a go routine so is
  // Non blocking