code: func WriteConfigToDisk(kubeletConfig *kubeletconfig.KubeletConfiguration, kubeletDir string) error {
  
  	kubeletBytes, err := getConfigBytes(kubeletConfig)
  	if err != nil {
  		return err
  	}
  	return writeConfigBytesToDisk(kubeletBytes, kubeletDir)
  }
docs: // WriteConfigToDisk writes the kubelet config object down to a file
  // Used at "kubeadm init" and "kubeadm upgrade" time