code: func (f *File) Render(spec *Specifier) (string, error) {
  	ret, err := f.Template[spec.TemplateName].Render(spec.Params)
  	if err != nil {
  		err = fmt.Errorf("rendering %q: %s", spec.TemplateName, err)
  	}
  	return ret, err
  }
docs: // Render renders the specified template with the given parameters.