Associate child record with parent using xrmservicetolkit in crm 2013 javascript

In this example I associate contact with an account

function associateRec()
{
var stdId = Xrm.Page.data.entity.getId();//get Account record's GUID
XrmServiceToolkit.Rest.Associate(
    stdId,
    "AccountSet",
    "0F383E15-1047-E511-80D7-3863BB3C5778",//contact record's GUID which u want to associate
    "ContactSet",
    "contact_customer_accounts",//account and contact relationship name
    function () {
         alert("Associated"); //Success - No Return Data - Do Something
    },
    function (error) {
         alert(error.message);
    },
    true
);
}