code: func searchXMLHandler(c *router.Context) {
  	c.Writer.Header().Set("Content-Type", "application/opensearchdescription+xml")
  	c.Writer.WriteHeader(http.StatusOK)
  	fmt.Fprintf(c.Writer, openSearchXML, c.Request.URL.Host)
  }
docs: // searchXMLHandler returns the opensearch document for this domain.