How to consume wsdl webservice through node js

I am using strong-soap node module i want to make call to webservice, I have wsdl file.

var soap = require('strong-soap').soap;
var WSDL = soap.WSDL;
var path = require('path');
var options = {};
WSDL.open('./wsdls/RateService_v22.wsdl',options,
  function(err, wsdl) {
    // You should be able to get to any information of this WSDL from this object. Traverse
    // the WSDL tree to get  bindings, operations, services, portTypes, messages,
    // parts, and XSD elements/Attributes.

    var service = wsdl.definitions.services['RateService'];
    //console.log(service.Definitions.call());
    //how to Call rateService ??
});