code: public String renderFlat(String template) {
      int depth = context.getRenderDepth();
  
      try {
        if (depth > config.getMaxRenderDepth()) {
          ENGINE_LOG.warn("Max render depth exceeded: {}", Integer.toString(depth));
          return template;
        } else {
          context.setRenderDepth(depth + 1);
          return render(parse(template), false);
        }
      } finally {
        context.setRenderDepth(depth);
      }
    }
docs: Parse the given string into a root Node, and then render it without processing any extend parents.
  This method should be used when the template is known to not have any extends or block tags.
  
  @param template
  string to parse
  @return rendered result