langchain/callbacks/tracers/stdout.py/ConsoleCallbackHandler/_on_llm_start
class ConsoleCallbackHandler:    def _on_llm_start(self, run: Run) -> None:
        crumbs = self.get_breadcrumbs(run)
        inputs = (
            {"prompts": [p.strip() for p in run.inputs["prompts"]]}
            if "prompts" in run.inputs
            else run.inputs
        )
        print(
            f"{get_colored_text('[llm/start]', color='green')} "
            + get_bolded_text(f"[{crumbs}] Entering LLM run with input:\n")
            + f"{try_json_stringify(inputs, '[inputs]')}"
        )