def headers(self) -> Optional[dict]:
        """
        Generate authentication headers.

        :return: A dictionary containing the authorization headers.
        """
        if self.folder_id is not None and self.api_key is not None:
            return {
                "Authorization": f"Api-key {self.api_key}",
                "x-folder-id": self.folder_id,
            }

        return None

        Generate authentication headers.

        :return: A dictionary containing the authorization headers.
        
llama-index-integrations/embeddings/llama-index-embeddings-yandexgpt/llama_index/embeddings/yandexgpt/util.py