How to use the ssh2-streams.utils function in ssh2-streams

var buffer = Buffer.alloc(16);
    return function randomCookie() {
      crypto.randomFillSync(buffer, 0, 16);
      return buffer.toString('hex');
    };
  } else {
    return function randomCookie() {
      return crypto.randomBytes(16).toString('hex');
    };
  }
})();

Client.Client = Client;
Client.Server = require('./server');
// pass some useful utilities on to end user (e.g. parseKey())
Client.utils = ssh2_streams.utils;
// expose useful SFTPStream constants for sftp server usage
Client.SFTP_STATUS_CODE = SFTPStream.STATUS_CODE;
Client.SFTP_OPEN_MODE = SFTPStream.OPEN_MODE;
// expose http(s).Agent implementations to allow easy tunneling of HTTP(S)
// requests
Client.HTTPAgent = HTTPAgents.SSHTTPAgent;
Client.HTTPSAgent = HTTPAgents.SSHTTPSAgent;

module.exports = Client; // backwards compatibility

var Client = require('../lib/client');
var Server = require('../lib/server');
var OPEN_MODE = require('ssh2-streams').SFTPStream.OPEN_MODE;
var STATUS_CODE = require('ssh2-streams').SFTPStream.STATUS_CODE;
var utils = require('ssh2-streams').utils;

var net = require('net');
var fs = require('fs');
var crypto = require('crypto');
var path = require('path');
var join = path.join;
var inspect = require('util').inspect;
var assert = require('assert');

var t = -1;
var group = path.basename(__filename, '.js') + '/';
var fixturesdir = join(__dirname, 'fixtures');

var USER = 'nodejs';
var PASSWORD = 'FLUXCAPACITORISTHEPOWER';
var MD5_HOST_FINGERPRINT = '64254520742d3d0792e918f3ce945a64';

var Server = require('../lib/server');
var utils = require('ssh2-streams').utils;

var fs = require('fs');
var path = require('path');
var join = path.join;
var assert = require('assert');
var spawn = require('child_process').spawn;
var exec = require('child_process').exec;

var t = -1;
var group = path.basename(__filename, '.js') + '/';
var fixturesdir = join(__dirname, 'fixtures');

var CLIENT_TIMEOUT = 5000;
var USER = 'nodejs';
var HOST_KEY_RSA = fs.readFileSync(join(fixturesdir, 'ssh_host_rsa_key'));
var HOST_KEY_DSA = fs.readFileSync(join(fixturesdir, 'ssh_host_dsa_key'));

var crypto = require('crypto');
var Socket = require('net').Socket;
var dnsLookup = require('dns').lookup;
var EventEmitter = require('events').EventEmitter;
var inherits = require('util').inherits;
var HASHES = crypto.getHashes();

var ssh2_streams = require('ssh2-streams');
var SSH2Stream = ssh2_streams.SSH2Stream;
var SFTPStream = ssh2_streams.SFTPStream;
var consts = ssh2_streams.constants;
var BUGS = consts.BUGS;
var ALGORITHMS = consts.ALGORITHMS;
var EDDSA_SUPPORTED = consts.EDDSA_SUPPORTED;
var parseKey = ssh2_streams.utils.parseKey;

var HTTPAgents = require('./http-agents');
var Channel = require('./Channel');
var agentQuery = require('./agent');
var SFTPWrapper = require('./SFTPWrapper');
var readUInt32BE = require('./buffer-helpers').readUInt32BE;

var MAX_CHANNEL = Math.pow(2, 32) - 1;
var RE_OPENSSH = /^OpenSSH_(?:(?![0-4])\d)|(?:\d{2,})/;
var DEBUG_NOOP = function(msg) {};

function Client() {
  if (!(this instanceof Client))
    return new Client();

  EventEmitter.call(this);

var net = require('net');
var EventEmitter = require('events').EventEmitter;
var listenerCount = EventEmitter.listenerCount;
var inherits = require('util').inherits;

var ssh2_streams = require('ssh2-streams');
var parseKey = ssh2_streams.utils.parseKey;
var SSH2Stream = ssh2_streams.SSH2Stream;
var SFTPStream = ssh2_streams.SFTPStream;
var consts = ssh2_streams.constants;
var DISCONNECT_REASON = consts.DISCONNECT_REASON;
var CHANNEL_OPEN_FAILURE = consts.CHANNEL_OPEN_FAILURE;
var ALGORITHMS = consts.ALGORITHMS;

var Channel = require('./Channel');
var KeepaliveManager = require('./keepalivemgr');
var writeUInt32BE = require('./buffer-helpers').writeUInt32BE;

var MAX_CHANNEL = Math.pow(2, 32) - 1;
var MAX_PENDING_AUTHS = 10;

var kaMgr;