langchain/tools/powerbi/tool.py/QueryPowerBITool/_run
class QueryPowerBITool:    def _run(
        self,
        tool_input: str,
        run_manager: Optional[CallbackManagerForToolRun] = None,
        **kwargs: Any,
    ) -> str:
        """Execute the query, return the results or an error message."""
        if cache := self._check_cache(tool_input):
            return cache

        try:
            query = self.llm_chain.predict(
                tool_input=tool_input,
                tables=self.powerbi.get_table_names(),
                schemas=self.powerbi.get_schemas(),
                examples=self.examples,
            )
        except Exception as exc:  # pylint: disable=broad-except
            self.session_cache[tool_input] = f"Error on call to LLM: {exc}"
            return self.session_cache[tool_input]
        if query == "I cannot answer this":
            self.session_cache[tool_input] = query
            return self.session_cache[tool_input]
        pbi_result = self.powerbi.run(command=query)
        result, error = self._parse_output(pbi_result)

        iterations = kwargs.get("iterations", 0)
        if error and iterations < self.max_iterations:
            return self._run(
                tool_input=RETRY_RESPONSE.format(
                    tool_input=tool_input, query=query, error=error
                ),
                run_manager=run_manager,
                iterations=iterations + 1,
            )

        self.session_cache[tool_input] = (
            result if result else BAD_REQUEST_RESPONSE.format(error=error)
        )
        return self.session_cache[tool_input]