langchain/llms/pipelineai.py/PipelineAI/_call
class PipelineAI:    def _call(
        self,
        prompt: str,
        stop: Optional[List[str]] = None,
        run_manager: Optional[CallbackManagerForLLMRun] = None,
    ) -> str:
        """Call to Pipeline Cloud endpoint."""
        try:
            from pipeline import PipelineCloud
        except ImportError:
            raise ValueError(
                "Could not import pipeline-ai python package. "
                "Please install it with `pip install pipeline-ai`."
            )
        client = PipelineCloud(token=self.pipeline_api_key)
        params = self.pipeline_kwargs or {}

        run = client.run_pipeline(self.pipeline_key, [prompt, params])
        try:
            text = run.result_preview[0][0]
        except AttributeError:
            raise AttributeError(
                f"A pipeline run should have a `result_preview` attribute."
                f"Run was: {run}"
            )
        if stop is not None:
            # I believe this is required since the stop tokens
            # are not enforced by the pipeline parameters
            text = enforce_stop_tokens(text, stop)
        return text