text: export default class PDFBackend {
    init = (source, element) => {
      const iframe = document.createElement('iframe');
  
      iframe.src = `/pdfjs-2.2.228-dist/web/viewer.html?file=${source}`;
      iframe.width = '100%';
      iframe.height = '100%';
  
      element.appendChild(iframe);
    }
  }