code: func (h *NegotiationHandler) WriteCreated(w http.ResponseWriter, r *http.Request, location string, e interface{}) {
  	switch httputil.NegotiateContentType(r, []string{}, "application/json") {
  	case "text/html":
  		h.html.WriteCreated(w, r, location, e)
  		return
  	case "text/plain":
  		h.plain.WriteCreated(w, r, location, e)
  		return
  	case "application/json":
  		h.json.WriteCreated(w, r, location, e)
  		return
  	default:
  		h.json.WriteCreated(w, r, location, e)
  		return
  	}
  }
docs: // WriteCreated writes a response object to the ResponseWriter with status code 201 and
  // the Location header set to location.