anchor.diff:        filename.click(loadFrom(diff));
       });
     }; // buildDiffFilenameHandlers()
  -
  -  // - - - - - - - - - - - - - - - - - - - - - - - -
  -
  -  const radioEntrySwitch = (previous, current) => {
  -    // See app/assets/stylesheets/wide-list-item.scss
  -    if (previous !== undefined) {
  -      previous.removeClass('selected');
  -    }
  -    $('.filename', $reviewPage).removeClass('selected');
  -    current.addClass('selected');
  -  };
   
     // - - - - - - - - - - - - - - - - - - - - - - - -
   
  
positive.code:         $(`.diff-deleted-line-count[data-filename="${filename}"]`).attr('disabled', false);
          $(`.diff-added-line-count[data-filename="${filename}"]`).attr('disabled', false);
  
          radioEntrySwitch(previousFilenameNode, filenameNode);
  
          if (previousFilenameNode !== undefined) {
            diffFileDiv(getFilename(previousFilenameNode)).hide();
  
negative.code:        index: param.nowIndex
      };
      $.getJSON('/reverter/revert', checkoutParams, (data) => {
        $reviewPage.hide();
        $kataPage.show();
        deleteAllFiles();
        insertNewFiles(data.visibleFiles);
        $('#test-button').click();
  