code: func WithCSRFProtection(fn HandlerFunc) httprouter.Handle {
  	hanlderFn := MakeHandler(fn)
  	return func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
  		err := csrf.VerifyHTTPHeader(r)
  		if err != nil {
  			log.Warningf("unable to validate CSRF token %v", err)
  			trace.WriteError(w, trace.AccessDenied("access denied"))
  			return
  		}
  		hanlderFn(w, r, p)
  	}
  }
docs: // WithCSRFProtection ensures that request to unauthenticated API is checked against CSRF attacks