How to use the notebook.transutils._ function in notebook

self.http_server.listen(port, self.ip)
            except socket.error as e:
                if e.errno == errno.EADDRINUSE:
                    self.log.info(_('The port %i is already in use, trying another port.') % port)
                    continue
                elif e.errno in (errno.EACCES, getattr(errno, 'WSAEACCES', errno.EACCES)):
                    self.log.warning(_("Permission to listen on port %i denied") % port)
                    continue
                else:
                    raise
            else:
                self.port = port
                success = True
                break
        if not success:
            self.log.critical(_('ERROR: the notebook server could not be started because '
                              'no available port could be found.'))
            self.exit(1)

"""initialize tornado webapp and httpserver"""
        self.tornado_settings['allow_origin'] = self.allow_origin
        self.tornado_settings['websocket_compression_options'] = self.websocket_compression_options
        if self.allow_origin_pat:
            self.tornado_settings['allow_origin_pat'] = re.compile(self.allow_origin_pat)
        self.tornado_settings['allow_credentials'] = self.allow_credentials
        self.tornado_settings['cookie_options'] = self.cookie_options
        self.tornado_settings['get_secure_cookie_kwargs'] = self.get_secure_cookie_kwargs
        self.tornado_settings['token'] = self.token

        # ensure default_url starts with base_url
        if not self.default_url.startswith(self.base_url):
            self.default_url = url_path_join(self.base_url, self.default_url)

        if self.password_required and (not self.password):
            self.log.critical(_("Notebook servers are configured to only be run with a password."))
            self.log.critical(_("Hint: run the following command to set a password"))
            self.log.critical(_("\t$ python -m notebook.auth password"))
            sys.exit(1)

        self.web_app = NotebookWebApplication(
            self, self.kernel_manager, self.contents_manager,
            self.session_manager, self.kernel_spec_manager,
            self.config_manager, self.extra_services,
            self.log, self.base_url, self.default_url, self.tornado_settings,
            self.jinja_environment_options,
        )
        ssl_options = self.ssl_options
        if self.certfile:
            ssl_options['certfile'] = self.certfile
        if self.keyfile:
            ssl_options['keyfile'] = self.keyfile

otherwise original SIGINT handler will be restored.
        
        This doesn't work on Windows.
        """
        info = self.log.info
        info(_('interrupted'))
        print(self.notebook_info())
        yes = _('y')
        no = _('n')
        sys.stdout.write(_("Shutdown this notebook server (%s/[%s])? ") % (yes, no))
        sys.stdout.flush()
        r,w,x = select.select([sys.stdin], [], [], 5)
        if r:
            line = sys.stdin.readline()
            if line.lower().startswith(yes) and no not in line.lower():
                self.log.critical(_("Shutdown confirmed"))
                # schedule stop on the main thread,
                # since this might be called from a signal handler
                self.io_loop.add_callback_from_signal(self.io_loop.stop)
                return
        else:
            print(_("No answer for 5s:"), end=' ')
        print(_("resuming operation..."))
        # no answer, or answer is no:
        # set it back to original SIGINT handler
        # use IOLoop.add_callback because signal.signal must be called
        # from main thread
        self.io_loop.add_callback_from_signal(self._restore_sigint_handler)

def _write_cookie_secret_file(self, secret):
        """write my secret to my secret_file"""
        self.log.info(_("Writing notebook server cookie secret to %s"), self.cookie_secret_file)
        try:
            with io.open(self.cookie_secret_file, 'wb') as f:
                f.write(secret)
        except OSError as e:
            self.log.error(_("Failed to write cookie secret to %s: %s"),
                           self.cookie_secret_file, e)
        try:
            os.chmod(self.cookie_secret_file, 0o600)
        except OSError:
            self.log.warning(
                _("Could not set permissions on %s"),
                self.cookie_secret_file
            )

This value will be returned from :meth:`WebSocketHandler.get_compression_options`.
        None (default) will disable compression.
        A dict (even an empty one) will enable compression.

        See the tornado docs for WebSocketHandler.get_compression_options for details.
        """)
    )
    terminado_settings = Dict(config=True,
            help=_('Supply overrides for terminado. Currently only supports "shell_command".'))

    cookie_options = Dict(config=True,
        help=_("Extra keyword arguments to pass to `set_secure_cookie`."
             " See tornado's set_secure_cookie docs for details.")
    )
    get_secure_cookie_kwargs = Dict(config=True,
        help=_("Extra keyword arguments to pass to `get_secure_cookie`."
             " See tornado's get_secure_cookie docs for details.")
    )
    ssl_options = Dict(config=True,
            help=_("""Supply SSL options for the tornado HTTPServer.
            See the tornado docs for details."""))
    
    jinja_environment_options = Dict(config=True, 
            help=_("Supply extra arguments that will be passed to Jinja environment."))

    jinja_template_vars = Dict(
        config=True,
        help=_("Extra variables to supply to jinja templates when rendering."),
    )
    
    enable_mathjax = Bool(True, config=True,
        help="""Whether to enable MathJax for typesetting math/TeX

websocket_compression_options = Any(None, config=True,
        help=_("""
        Set the tornado compression options for websocket connections.

        This value will be returned from :meth:`WebSocketHandler.get_compression_options`.
        None (default) will disable compression.
        A dict (even an empty one) will enable compression.

        See the tornado docs for WebSocketHandler.get_compression_options for details.
        """)
    )
    terminado_settings = Dict(config=True,
            help=_('Supply overrides for terminado. Currently only supports "shell_command".'))

    cookie_options = Dict(config=True,
        help=_("Extra keyword arguments to pass to `set_secure_cookie`."
             " See tornado's set_secure_cookie docs for details.")
    )
    get_secure_cookie_kwargs = Dict(config=True,
        help=_("Extra keyword arguments to pass to `get_secure_cookie`."
             " See tornado's get_secure_cookie docs for details.")
    )
    ssl_options = Dict(config=True,
            help=_("""Supply SSL options for the tornado HTTPServer.
            See the tornado docs for details."""))
    
    jinja_environment_options = Dict(config=True, 
            help=_("Supply extra arguments that will be passed to Jinja environment."))

    jinja_template_vars = Dict(
        config=True,
        help=_("Extra variables to supply to jinja templates when rendering."),

jsonrpc_ws_proxy = Unicode(help=_("path to jsonrpc-ws-proxy/dist/server.js")).tag(
        config=True
    )

    nodejs = Unicode(help=_("path to nodejs executable")).tag(config=True)

    autodetect = Bool(
        True, help=_("try to find known language servers in sys.prefix (and elsewhere)")
    ).tag(config=True)

    node_roots = List_([], help=_("absolute paths in which to seek node_modules")).tag(
        config=True
    )

    extra_node_roots = List_(
        [], help=_("additional absolute paths to seek node_modules first")
    ).tag(config=True)

    cmd = List_().tag(config=True)

    @default("nodejs")
    def _default_nodejs(self):
        return (
            shutil.which("node") or shutil.which("nodejs") or shutil.which("nodejs.exe")
        )

    @default("jsonrpc_ws_proxy")
    def _default_jsonrpc_ws_proxy(self):
        """ try to find jsonrpc-ws-proxy

        the `which` is an imaginary case where it has been compiled, somehow
        """

try:
            with io.open(self.cookie_secret_file, 'wb') as f:
                f.write(secret)
        except OSError as e:
            self.log.error(_("Failed to write cookie secret to %s: %s"),
                           self.cookie_secret_file, e)
        try:
            os.chmod(self.cookie_secret_file, 0o600)
        except OSError:
            self.log.warning(
                _("Could not set permissions on %s"),
                self.cookie_secret_file
            )

    token = Unicode('',
        help=_("""Token used for authenticating first-time connections to the server.

        When no password is enabled,
        the default is to generate a new, random token.

        Setting to an empty string disables authentication altogether, which is NOT RECOMMENDED.
        """)
    ).tag(config=True)

    _token_generated = True

    @default('token')
    def _token_default(self):
        if os.getenv('JUPYTER_TOKEN'):
            self._token_generated = False
            return os.getenv('JUPYTER_TOKEN')
        if self.password:

help=_("""Extra paths to search for serving jinja templates.

        Can be used to override templates from notebook.templates.""")
    )

    @property
    def template_file_path(self):
        """return extra paths + the default locations"""
        return self.extra_template_paths + DEFAULT_TEMPLATE_PATH_LIST

    extra_nbextensions_path = List(Unicode(), config=True,
        help=_("""extra paths to look for Javascript notebook extensions""")
    )

    extra_services = List(Unicode(), config=True,
        help=_("""handlers that should be loaded at higher priority than the default services""")
    )
    
    @property
    def nbextensions_path(self):
        """The path to look for Javascript notebook extensions"""
        path = self.extra_nbextensions_path + jupyter_path('nbextensions')
        # FIXME: remove IPython nbextensions path after a migration period
        try:
            from IPython.paths import get_ipython_dir
        except ImportError:
            pass
        else:
            path.append(os.path.join(get_ipython_dir(), 'nbextensions'))
        return path

    websocket_url = Unicode("", config=True,

custom_display_url = Unicode(u'', config=True,
        help=_("""Override URL shown to users.

        Replace actual URL, including protocol, address, port and base URL,
        with the given value when displaying URL to the users. Do not change
        the actual connection URL. If authentication token is enabled, the
        token is added to the custom URL automatically.

        This option is intended to be used when the URL to display to the user
        cannot be determined reliably by the Jupyter notebook server (proxified
        or containerized setups for example).""")
    )

    port = Integer(8888, config=True,
        help=_("The port the notebook server will listen on.")
    )

    port_retries = Integer(50, config=True,
        help=_("The number of additional ports to try if the specified port is not available.")
    )

    certfile = Unicode(u'', config=True, 
        help=_("""The full path to an SSL/TLS certificate file.""")
    )
    
    keyfile = Unicode(u'', config=True, 
        help=_("""The full path to a private key file for usage with SSL/TLS.""")
    )
    
    client_ca = Unicode(u'', config=True,
        help=_("""The full path to a certificate authority certificate for SSL/TLS client authentication.""")