        )
        if settings.callback_options is None:
            settings.callback_options = self.default_callback_options
        self.success_handler = settings.callback_options.success
        self.failure_handler = settings.callback_options.failure

    @property
    def client(self) -&gt; WebClient:
        if self._client is None:
            self._client = create_web_client(logger=self.logger)
        return self._client

    @property
    def logger(self) -&gt; Logger:
        if self._logger is 