How to use the keystonemiddleware.auth_token._exceptions function in keystonemiddleware

def _assert_token_not_expired(self, token_expires):
        if timeutils.utcnow() > timeutils.normalize_time(token_expires):
            raise _exceptions.InvalidToken()

:param request: Incoming request
        :type request: _request.AuthTokenRequest

        """
        user_auth_ref = None
        serv_auth_ref = None
        allow_expired = False

        if request.service_token:
            self.log.debug('Authenticating service token')
            try:
                _, serv_auth_ref = self._do_fetch_token(request.service_token)
                self._validate_token(serv_auth_ref)
                self._confirm_token_bind(serv_auth_ref, request)
            except ksm_exceptions.InvalidToken:
                self.log.info('Invalid service token')
                request.service_token_valid = False
            else:
                # FIXME(jamielennox): The new behaviour for service tokens is
                # that they have to pass the policy check to be allowed.
                # Previously any token was accepted here. For now we will
                # continue to mark service tokens as valid if they are valid
                # but we will only allow service role tokens to do
                # allow_expired. In future we should reject any token that
                # isn't a service token here.
                role_names = set(serv_auth_ref.role_names)
                check = self._service_token_roles.intersection(role_names)
                role_check_passed = bool(check)

                # if service_token_roles_required then the service token is
                # only valid if the roles check out. Otherwise at this point it

def check(self, token_ids):
        if self._any_revoked(token_ids):
            self._log.debug('Token is marked as having been revoked')
            raise exc.InvalidToken(_('Token has been revoked'))

def auth_filter(app):
        return AuthProtocol(app, conf)
    return auth_filter


def app_factory(global_conf, **local_conf):
    conf = global_conf.copy()
    conf.update(local_conf)
    return AuthProtocol(None, conf)


# NOTE(jamielennox): Maintained here for public API compatibility.
InvalidToken = ksm_exceptions.InvalidToken
ServiceError = ksm_exceptions.ServiceError
ConfigurationError = ksm_exceptions.ConfigurationError

def verify():
            try:
                signing_cert_path = self._signing_directory.calc_path(
                    self._SIGNING_CERT_FILE_NAME)
                signing_ca_path = self._signing_directory.calc_path(
                    self._SIGNING_CA_FILE_NAME)
                return cms.cms_verify(data, signing_cert_path,
                                      signing_ca_path,
                                      inform=inform).decode('utf-8')
            except (ksc_exceptions.CMSError,
                    cms.subprocess.CalledProcessError) as err:
                self.log.warning(_LW('Verify error: %s'), err)
                msg = _('Token authorization failed')
                raise ksm_exceptions.InvalidToken(msg)