shelly.call "http.get" - issue, can anyone see my error?

in an Shelly.addStatusHandler() that seems to work and if i use switch.set ir works and all.. bu below does not work i get the error below shelly.call

let ip = '10.0.1.153';
let heater_url = 'http://' + ip + '/rpc/Switch.Set?id=0&on='true;
shelly.call("http.get",{url: 'http://' + heater_url },function (result, code, msg, ud) {},null);

erroronStatusChange callback error: [shelly] is not defined

i have try'd both with and without "http://" alså fixing the syntax.. the url is an object as should be supported by shelly.call as params.