code: func NewImageManager(recorder record.EventRecorder, imageService kubecontainer.ImageService, imageBackOff *flowcontrol.Backoff, serialized bool, qps float32, burst int) ImageManager {
  	imageService = throttleImagePulling(imageService, qps, burst)
  
  	var puller imagePuller
  	if serialized {
  		puller = newSerialImagePuller(imageService)
  	} else {
  		puller = newParallelImagePuller(imageService)
  	}
  	return &imageManager{
  		recorder:     recorder,
  		imageService: imageService,
  		backOff:      imageBackOff,
  		puller:       puller,
  	}
  }
docs: // NewImageManager instantiates a new ImageManager object.