Jupyterhub username argument in page.html

I changed the TmpAuthenticator project of Jupyterhub 0.96 and want the request with the token argument, like the code is below:

from traitlets import Bool
from tornado import gen

from jupyterhub.auth import Authenticator
from jupyterhub.handlers import BaseHandler
from jupyterhub.utils import url_path_join

class TmpAuthenticateHandler(BaseHandler):
Handler for /login

Creates a new user with a random UUID, and auto starts their server
def initialize(self, force_new_server, process_user):
    self.force_new_server = force_new_server
    self.process_user = process_user

def get(self):
    raw_user = yield self.get_current_user()
        # username = str(uuid.uuid4())
        # username = self.get_argument("user")  
        username = self.get_argument("token")  
        raw_user = self.user_from_username(username)
    user = yield gen.maybe_future(self.process_user(raw_user, self))

class TmpAuthenticator(Authenticator):
JupyterHub Authenticator for use with tmpnb.org

When JupyterHub is configured to use this authenticator, visiting the home
page immediately logs the user in with a randomly generated UUID if they
are already not logged in, and spawns a server for them.

auto_login = True
login_service = 'tmp'

force_new_server = Bool(
    Stop the user's server and start a new one when visiting /hub/login

    When set to True, users going to /hub/login will *always* get a
    new single-user server. When set to False, they'll be
    redirected to their current session if one exists.

def process_user(self, user, handler):
    Do additional arbitrary things to the created user before spawn.

    user is a user object, and handler is a TmpAuthenticateHandler object

    Should return the new user object.

    This method can be a @tornado.gen.coroutine.

    Note: This is primarily for overriding in subclasses
    return user

def get_handlers(self, app):
    # FIXME: How to do this better?
    extra_settings = {
        'force_new_server': self.force_new_server,
        'process_user': self.process_user

    return [
        ('/login', TmpAuthenticateHandler, extra_settings)

def login_url(self, base_url):
    return url_path_join(base_url, 'login')

If I want add a navigator and the link is the base url + token(which is the request token argument), so that the link could be the request with token. I know it could be done by use jinja which is used by jupyterhub, and I can design the link like “/beta?token={token}”. My question is how i can pass or get the token argument in the handler, and get it in the page.html? Thanks!