How to use the openvidu-node-client.Session function in openvidu-node-client

/* CONFIGURATION */

var OpenVidu = require('openvidu-node-client').OpenVidu;
var Session = require('openvidu-node-client').Session;
var OpenViduRole = require('openvidu-node-client').OpenViduRole;
var TokenOptions = require('openvidu-node-client').TokenOptions;

// Check launch arguments: must receive openvidu-server URL and the secret
if (process.argv.length != 4) {
    console.log("Usage: node " + __filename + " OPENVIDU_URL OPENVIDU_SECRET");
    process.exit(-1);
}
// For demo purposes we ignore self-signed certificate
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0"

// Node imports
var express = require('express');
var fs = require('fs');
var session = require('express-session');
var https = require('https');