anchor.diff:    // refresh [<] tag [>]
     //-----------------------------------------
   
  -  var refreshTagControls = function() {
  -    var colour = param.lights[param.nowTag - 1].colour;
  -    var minTag = 1;
  -    var maxTag = param.lights.length;
  -    var hasPrevTag = minTag < param.nowTag;
  -    var hasNextTag =          param.nowTag < maxTag;
  +  const refreshTagControls = () => {
  +    const colour = param.lights[param.nowTag - 1].colour;
  +    const minTag = 1;
  +    const maxTag = param.lights.length;
  +    const hasPrevTag = minTag < param.nowTag;
  +    const hasNextTag =          param.nowTag < maxTag;
   
       $('#now-tag-number')
         .removeClass()
  
positive.code:   // The [revert] button is available only from the review *dialog*.
    //---------------------------------------------------------------------
  
    cd.setReviewDialogData = function(id, avatar, wasTag, nowTag, filename) {
      param = {
        id:id,
        avatar:avatar,
        wasTag:wasTag,
        nowTag:nowTag,
        filename:filename
      };
      reviewRefresh();
    };
  
    var param = {
            id: "<%= @kata.id %>",
        avatar: "<%= @avatar.name %>",
        wasTag: "<%= @was_tag %>",
  
negative.code: 
    // - - - - - - - - - - - - - - - - - - - - - - - -
  
    const makeDiffDeletedCountColumn = (diffs) => {
      return makeDiffCountColumn(diffs, 'deleted_line_count', 'deleted');
    };
  
    const makeDiffAddedCountColumn = (diffs) => {
      return makeDiffCountColumn(diffs, 'added_line_count', 'added');
    };
  
    const makeDiffCountColumn = (diffs, propertyName, cssName) => {
      let html = '';
      if (!diffCheckBox().is(':checked')) {
        return html;
      }
      html += '<table>';
      $.each(sortedDiffs(diffs), function(_, diff) {
        const count = diff[propertyName];
        const td = $('<td>');
        const noneOrSome = (count == 0) ? 'none' : 'some';
        const div = $('<div>', {
          'class': 'diff-' + cssName + '-line-count ' + noneOrSome + ' button',
          'data-filename': diff.filename
        });
  