* compatibility with cloudinary (see scripts/cloudinary.js) * helper has to be registered via a function - https://github.com/hexojs/hexo/issues/1462#issuecomment-277474592 - https://github.com/hexojs/hexo/issues/743#issuecomment-168262852 - https://hexo.io/api/helper - https://github.com/hexojs/hexo/blob/master/lib/plugins/helper/open_graph.js