anchor.diff:  
     // - - - - - - - - - - - - - - - - - - - - - - - -
     const buildDiffFilenameHandlers = (diffs) => {
  -    // Builds filename click handlersfor a [ kata-id, was-index, now-index] tuple.
       const clicked = [];
  -    const whenReClickedScrollToNextDiffChunk = (diff, filename) => {
  -      const firstClick = (filename) => !clicked.includes(filename);
  -      const reClicked = (filename) => param.filename === filename;
  -      if (diff.section_count > 0 && (firstClick(filename) || reClicked(filename))) {
  -        const $diffSheet = $(`[id="diff_file_content_for_${filename}"]`);
  -        const section = $(`#${diff.id}_section_${diff.section_index}`);
  -        const halfSecond = 500;
  -        $diffSheet.animate({
  -          scrollTop: '+=' + (section.offset().top - 250) + 'px'
  -        }, halfSecond);
  -        diff.section_index += 1;
  -        diff.section_index %= diff.section_count;
  -      }
  -    };
  -
       diffs.forEach(diff => {
         const filename = diffFilename(diff);
         diff.section_index = 0;
  
positive.code:         selectLineCounts(filename);
          selectFilename(diff.id);
          selectFile(filename);
          whenReClickedScrollToNextDiffChunk(diff, filename);
          param.filename = filename;
          clicked.push(filename);
        });
  
negative.code:     $('.diff-line-count').attr('disabled', true);
      $(`.diff-line-count[data-filename="${filename}"]`).attr('disabled', false);
    };
  
    const selectFilename = (id) => {
      $('.diff-filename', $reviewPage).removeClass('selected');
      $(`#radio_${id}`, $reviewPage).addClass('selected');
    };
  
    const selectFile = (filename) => {
      $('.filename_div', $reviewPage).hide();
      $(`[id="${filename}_diff_div"]`).show();
    };
  
    const whenReClickedScrollToNextDiffChunk = (clicked, diff, filename) => {
      const firstClick = (filename) => !clicked.includes(filename);
      const reClicked = (filename) => param.filename === filename;
      if (diff.section_count > 0 && (firstClick(filename) || reClicked(filename))) {
        const $diffSheet = $(`[id="diff_file_content_for_${filename}"]`);
        const section = $(`#${diff.id}_section_${diff.section_index}`);
        const halfSecond = 500;
        $diffSheet.animate({
          scrollTop: '+=' + (section.offset().top - 250) + 'px'
        }, halfSecond);
        diff.section_index += 1;
        diff.section_index %= diff.section_count;
      }
    };
  
    // - - - - - - - - - - - - - - - - - - - - - - - -
  