def _create_chat_completion(
        self,
        prompt: Optional[str] = None,
        messages: Optional[Sequence[Dict]] = None,
        **kwargs,
    ) -> str:
        """
        Fake chat completion.

        Returns:
            Completion model response.
        """

        if prompt is None:
            prompt = json.dumps(messages)

        return self.endpoint.api.completion(
            model=self.model_engine, prompt=prompt, **kwargs
        )["completion"]

        Fake chat completion.

        Returns:
            Completion model response.
        
src/feedback/trulens/feedback/dummy/provider.py