const virtualDOM = {
  type: 'html',
  props: { lang: 'ko' },
  children: [
    {
      type: 'head',
      props: null,
      children: [
        {
          type: 'meta',
          props: { charset: 'UTF-8' },
          children: null
        },
        {
          type: 'title',
          props: null,
          children: [{ type: 'text', text: 'Document Object Model' }]
        }
      ]
    },