code: function prependTitle(html, title, svgWidth) {
          if (!title || !svgWidth) {
              return html;
          }
          let {grey} = colorSchemas;
  
          html =  html.replace(/<g/,`<text x="${this.margin().left}" y="${config.titleTopOffset}" font-family="${config.titleFontFamily}" font-size="${config.titleFontSize}" fill="${grey[6]}"> ${title} </text><g `);
  
          return html;
      }
docs: if passed, append title to the raw html to appear on graph
  @param  {string} html     raw html string
  @param  {string} title    title of the graph
  @param  {number} svgWidth width of graph container
  @return {string}         raw html with title prepended