langchain/callbacks/clearml_callback.py/ClearMLCallbackHandler/on_chain_start
class ClearMLCallbackHandler:    def on_chain_start(
        self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any
    ) -> None:
        """Run when chain starts running."""
        self.step += 1
        self.chain_starts += 1
        self.starts += 1

        resp = self._init_resp()
        resp.update({"action": "on_chain_start"})
        resp.update(flatten_dict(serialized))
        resp.update(self.get_custom_callback_meta())

        chain_input = inputs["input"]

        if isinstance(chain_input, str):
            input_resp = deepcopy(resp)
            input_resp["input"] = chain_input
            self.on_chain_start_records.append(input_resp)
            self.action_records.append(input_resp)
            if self.stream_logs:
                self.logger.report_text(input_resp)
        elif isinstance(chain_input, list):
            for inp in chain_input:
                input_resp = deepcopy(resp)
                input_resp.update(inp)
                self.on_chain_start_records.append(input_resp)
                self.action_records.append(input_resp)
                if self.stream_logs:
                    self.logger.report_text(input_resp)
        else:
            raise ValueError("Unexpected data format provided!")