code: func (ipc ImagePullCheck) Check() (warnings, errorList []error) {
  	for _, image := range ipc.imageList {
  		ret, err := ipc.runtime.ImageExists(image)
  		if ret && err == nil {
  			klog.V(1).Infof("image exists: %s", image)
  			continue
  		}
  		if err != nil {
  			errorList = append(errorList, errors.Wrapf(err, "failed to check if image %s exists", image))
  		}
  		klog.V(1).Infof("pulling %s", image)
  		if err := ipc.runtime.PullImage(image); err != nil {
  			errorList = append(errorList, errors.Wrapf(err, "failed to pull image %s", image))
  		}
  	}
  	return warnings, errorList
  }
docs: // Check pulls images required by kubeadm. This is a mutating check