code: def buildhtml(self):
          
          self.buildcontent()
          self.buildhtmlheader()
          self.content = self._htmlcontent.decode('utf-8') # need to ensure unicode
          self._htmlcontent = self.template_page_highcharts.render(chart=self)
          return self._htmlcontent
docs: Build the HTML page
          Create the htmlheader with css / js
          Create html page