def yield_html
      if (template_path = attrs.content_template_path)
        @yield_renderer ||= StringTemplateRenderer.new(@volt_app, attrs.content_controller, template_path)
        @yield_renderer.html
      else
        # no template, empty string
        ''
      end
    end
def yield_html
      if (template_path = attrs.content_template_path)
        @yield_renderer ||= StringTemplateRenderer.new(@volt_app, attrs.content_controller, template_path)
        @yield_renderer.html
      else
        # no template, empty string
        ''
      end
    end
yield_html renders the content passed into a tag as a string.  You can ```.watch!```
 ```yield_html``` and it will be run again when anything in the template changes.