def client(self) -> OpenAI:
        """Get the OpenAI client.

        Returns:
            OpenAI: Initialized OpenAI client instance

        Raises:
            ImportError: If OpenAI package is not installed
        """
        if OpenAI is None:
            msg = "OpenAI is not installed. Please install it to use ChatGPT backend."
            raise ImportError(msg)
        if self._client is None:
            self._client = OpenAI(api_key=self.api_key)
        return self._client
Get the OpenAI client.

        Returns:
            OpenAI: Initialized OpenAI client instance

        Raises:
            ImportError: If OpenAI package is not installed
        
src/anomalib/models/image/vlm_ad/backends/chat_gpt.py