anchor.diff:    const makeTrafficLightsHtml = () => {
       let html = '';
       let wasIndex = 0;
  -    let lastColour = '';
  -    let trafficLightCount = 0;
       html += '<table><tr>';
       $.each(param.events, (_n, event) => {
         const colour = event.colour;
  
positive.code:     $.getJSON('/differ/diff', reviewParams, (data) => {
        $('.ui-dialog').removeClass('busy');
        param = data;
        refreshTrafficLights();
        refreshEventControls();
        refreshFiles();
        refreshForkButton();
        refreshRevertButton();
  
negative.code:         const barOrGap = (param.nowIndex === nowIndex) ? 'bar' : 'gap';
          html += makeTd(makeTrafficLightHtml(colour, wasIndex, nowIndex, barOrGap));
          wasIndex = nowIndex;
        }
      });
      html += makeTd(makeAvatarImageHtml());
      html += '</tr></table>';
      return html;
    };
  
  