k.firstChild);
          });
        }

      if (navigator && navigator.clipboard) {
        addCopyButtons(navigator.clipboard);
      } else {
        var script = document.createElement('script');
        script.src = 'https://cdnjs.cloudflare.com/ajax/libs/clipboard-polyfill/2.7.0/clipboard-polyfill.promise.js';
        script.integrity = 'sha256-waClS2re9NUbXRsryKoof+F9qc1gjjIhc2eT7ZbIv94=';
        script.crossOrigin = 'anonymous';
        script.onload = function() {
          addCopyButtons(clipboa