anchor.diff:      $('.diff-line-count').attr('disabled', true);
       $(`.diff-line-count[data-diff-id="${diff.id}"]`).attr('disabled', false);
       // show file content
  -    $('.filename_div', review.page).hide();
  -    $(`#${diff.id}_diff_div`).show();
  +    $('.file_content_div', review.page).hide();
  +    $(`#${diff.id}_file_content_div`).show();
   
       scrollToNextDiffChunkOnReclick(diff, diff.filename);
       review.filename = diff.filename;
  
positive.code:     const lineNumbers = makeLineNumbers(diff.lines);
      const fileContent = makeContent(diff.id, diff.lines);
      const $file = $('' +
        `<div id="${diff.id}_diff_div" class="filename_div">` +
        '<table>' +
          '<tr class="valign-top">' +
            makeTd('<div class="diff-line-numbers"></div>') +
  
negative.code:       if ($node.html() === '&nbsp;') { return; }
        if ($node.attr('disabled') !== 'disabled') {
          const id = $node.data('diff-id');
          const selector = `[id="${id}_file_content_div"] ${type}`;
          $(selector).css('display', value);
          if (value === 'none') {
            $node.removeClass('on').addClass('off');
  