code: protected RawData __render(String template) {
          if (null == template) return new RawData("");
          return S.raw(__engine.sandbox().render(template, __renderArgs));
      }
docs: Render another template from within this template. Using the renderArgs
  of this template.
  
  @param template
  @return render result as {@link org.rythmengine.utils.RawData}
  @see #__render(String, Object...)