How to use the rpcq.ClientAuthConfig function in rpcq

def _get_client_auth_config(self) -> Optional[ClientAuthConfig]:
        if not self.session:
            return
        if self.session.config.engagement is not None:
            # We store the engagement used to construct this client so that we can later check
            # for validity
            self._client_engagement = self.session.config.engagement
            return ClientAuthConfig(
                client_public_key=self._client_engagement.client_public_key,
                client_secret_key=self._client_engagement.client_secret_key,
                server_public_key=self._client_engagement.server_public_key,
            )