code: function drawTitles() {
              if (hasTitle()) {
                  // either use title provided from the data
                  // or customTitle provided via API method call
                  if (legendGroup) {
                      legendGroup.remove();
                  }
  
                  legendGroup = svg.select('.metadata-group')
                    .append('g')
                      .classed('legend-group', true)
                      .attr('transform', `translate(0, ${chartHeight / 2})`);
  
  
                  // override title with customTitle if given
                  if (customTitle) {
                      title = customTitle;
                  }
  
                  titleEl = legendGroup.selectAll('text.bullet-title')
                    .data([1])
                    .enter()
                      .append('text')
                        .attr('class', 'bullet-title x-axis-label')
                        .text(title);
  
                  // either use subtitle provided from the data
                  // or customSubtitle provided via API method call
                  if (subtitle || customSubtitle) {
  
                      // override subtitle with customSubtitle if given
                      if (customSubtitle) {
                          subtitle = customSubtitle;
                      }
  
                      titleEl = legendGroup.selectAll('text.bullet-subtitle')
                        .data([1])
                        .enter()
                          .append('text')
                            .attr('class', 'bullet-subtitle x-axis-label')
                            .attr('y', subtitleSpacing)
                            .text(subtitle);
                  }
              }
          }
docs: Draws the title and subtitle components of chart
  @return {void}
  @private