docs: function convertToNode (element) {
    switch (element.type) {
      case 'tag':
        return ['a', 'p', 'strong', 'em', 'b', 'em'].indexOf(element.name) !== -1
             ? {
               name: element.name,
               attrs: filterAttributes(element.name, element.attribs),
               children: element
                 .children
                 .map(child => convertToNode(child))
                 .filter(child => child !== null)
             }
             : null
  
      case 'text':
        return element.data
  
      default:
        return '---'
    }
  }