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

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
RevocationListError = ksm_exceptions.RevocationListError

def _verify_signing_dir(self):
        if os.path.isdir(self._directory_name):
            if not os.access(self._directory_name, os.W_OK):
                raise exc.ConfigurationError(
                    _('unable to access signing_dir %s') %
                    self._directory_name)
            uid = os.getuid()
            if os.stat(self._directory_name).st_uid != uid:
                self._log.warning('signing_dir is not owned by %s', uid)
            current_mode = stat.S_IMODE(os.stat(self._directory_name).st_mode)
            if current_mode != stat.S_IRWXU:
                self._log.warning(
                    'signing_dir mode is %(mode)s instead of %(need)s',
                    {'mode': oct(current_mode), 'need': oct(stat.S_IRWXU)})
        else:
            os.makedirs(self._directory_name, stat.S_IRWXU)

# Also add the deprecated name with the same type and dest.
        for d_o in o.deprecated_opts:
            opt_types[d_o.name] = type_dest

    opts = {}
    for k, v in six.iteritems(conf):
        dest = k
        try:
            if v is not None:
                type_, dest = opt_types[k]
                v = type_(v)
        except KeyError:
            # This option is not known to auth_token.
            pass
        except ValueError as e:
            raise ksm_exceptions.ConfigurationError(
                _('Unable to convert the value of %(key)s option into correct '
                  'type: %(ex)s') % {'key': k, 'ex': e})
        opts[dest] = v
    return opts

def __init__(self, log, security_strategy, secret_key, **kwargs):
        super(SecureTokenCache, self).__init__(log, **kwargs)

        if not secret_key:
            msg = _('memcache_secret_key must be defined when a '
                    'memcache_security_strategy is defined')
            raise exc.ConfigurationError(msg)

        if isinstance(security_strategy, six.string_types):
            security_strategy = security_strategy.encode('utf-8')
        if isinstance(secret_key, six.string_types):
            secret_key = secret_key.encode('utf-8')

        self._security_strategy = security_strategy
        self._secret_key = secret_key