How to use the gaiatest.GaiaDevice function in gaiatest

def run(self, args=sys.argv[1:]):
        args = self.parser.parse_args()

        host, port = args.address.split(':')
        self.marionette = Marionette(host=host, port=int(port))
        self.marionette.start_session()

        self.apps = gaiatest.GaiaApps(self.marionette)
        self.data_layer = gaiatest.GaiaData(self.marionette)
        self.device = gaiatest.GaiaDevice(self.marionette)

        ret = args.func(args)
        if ret is None:
            ret = 0

        self.marionette.delete_session()

        sys.exit(ret)

def install_apps():
        mc = get_marionette(args)
        device = GaiaDevice(mc)
        try:
            device.restart_b2g()
            print 'Your device is rebooting.'
        except Exception:
            print ' ** Check to make sure you don\'t have desktop B2G running'
            raise

        apps = GaiaApps(mc)
        apps.kill_all()

        lockscreen = LockScreen(mc)
        lockscreen.unlock()

        if args.wifi_ssid:
            print 'Configuring WiFi'
            if not args.wifi_key or not args.wifi_pass:

self.device_serial = device_serial
        self.marionette = marionette

        settings = gaiatest.GaiaData(self.marionette).all_settings
        mac_address = self.marionette.execute_script(
            'return navigator.mozWifiManager && '
            'navigator.mozWifiManager.macAddress;')

        self.submit_report = True
        self.ancillary_data = {
            'generated_by': 'b2gperf %s' % __version__,
            'build_url': datazilla_config['build_url']}

        dm = mozdevice.DeviceManagerADB(deviceSerial=self.device_serial)
        self.device = gaiatest.GaiaDevice(self.marionette, manager=dm)

        version = mozversion.get_version(sources=sources, dm_type='adb',
                                         device_serial=self.device_serial)
        self.ancillary_data['build_revision'] = version.get('build_changeset')
        self.ancillary_data['gaia_revision'] = version.get('gaia_changeset')
        self.ancillary_data['gecko_repository'] = version.get('application_repository')
        self.ancillary_data['gecko_revision'] = version.get('application_changeset')
        self.ancillary_data['ro.build.version.incremental'] = version.get(
            'device_firmware_version_incremental')
        self.ancillary_data['ro.build.version.release'] = version.get(
            'device_firmware_version_release')
        self.ancillary_data['ro.build.date.utc'] = version.get(
            'device_firmware_date')

        self.required = {
            'generated_by': self.ancillary_data.get('generated_by'),

def do_login(args):
    mc = get_marionette(args)
    device = GaiaDevice(mc)
    apps = GaiaApps(mc)
    data_layer = GaiaData(mc)

    _persona_frame_locator = ('css selector', "iframe")

    # Trusty UI on home screen
    _tui_container_locator = ('id', 'trustedui-frame-container')

    # Persona dialog
    _waiting_locator = ('css selector', 'body.waiting')
    _email_input_locator = ('id', 'authentication_email')
    _password_input_locator = ('id', 'authentication_password')
    _new_password = ('id', 'password')
    _verify_new_password = ('id', 'vpassword')
    _next_button_locator = ('css selector', 'button.start')
    _verify_start_button = ('css selector', 'button#verify_user')