code: func (b *bundle) GenerateEmail(templateName string, input *EmailTemplateInput) (subject, body string) {
  	var err error
  	if subject, body, err = b.executeUserTemplate(templateName, input); err != nil {
  		// Execution of the user-defined template failed.
  		// Fallback to the error template.
  		subject, body = b.executeErrorTemplate(templateName, input, err)
  	}
  	return
  }
docs: // GenerateEmail generates an email using the named template. If the template
  // fails, an error template is used, which includes error details and a link to
  // the definition of the failed template.