code: function updateTitle(dataPoint) {
              let tTitle = title;
              let formattedDate = formatDate(new Date(dataPoint[dateLabel]));
  
              if (tTitle.length) {
                  if (shouldShowDateInTitle) {
                      tTitle = `${tTitle} - ${formattedDate}`;
                  }
              } else {
                  tTitle = formattedDate;
              }
  
              tooltipTitle.text(tTitle);
          }
docs: Updates value of tooltipTitle with the data meaning and the date
  @param  {Object} dataPoint Point of data to use as source
  @return void
  @private