How to create catalog item automatically using Cart API script ServiceNow

var cartId = GlideGuid.generate(null);
var cart = new Cart(cartId);
 var item = cart.addItem('4054428fdb151f0097679ec6db9619c0', 1); // sys_id of the catalog item
 //fill in the variables on the request item form
cart.setVariable(item,"requested_for", "sys_id"); 
cart.setVariable(item,"contact_number", "+1 1231212344");
cart.setVariable(item,"assignment_group", "sys_id"); 
cart.setVariable(item,"short_description", "Welcome to workingcode.in");
var rc = cart.placeOrder();