code: function getTocNode (tree) {
    const tocNode = toc(tree, { maxDepth: 3, loose: false })
  
    if (!tocNode.map || !tocNode.map.children[0] || !tocNode.map.children[0].children[1]) {
      return
    }
  
    return {
      type: 'TocNode',
      data: {
        hName: 'div',
        hProperties: {
          className: ['toc-container']
        }
      },
      children: [
        {
          type: 'TocTitleNode',
          data: {
            hName: 'h2'
          },
          children: [{ type: 'text', value: 'Table of contents' }]
        },
        tocNode.map.children[0].children[1]
      ]
    }
  }
docs: Returns the node for TOC
  
  @method getTocNode
  
  @param  {Object}   tree
  
  @return {Object}