Allow Optional Inputs about burr HOT 2 CLOSED

@action(read=["relevant_vars", "task", "prompt"], writes=["plan_prompt"])
def create_plan_prompt(state: State) -> Tuple[dict, State]:
    if state["task"] == "Clear the table":
        plan_prompt = f"""Create a plan for a robot to remove the following objects from the table:
            {state["relevant_vars"]["objects_on_table"]}
            Do not add any extra steps.
        """
    else:
        plan_prompt = "Unknown task"
    result = {"plan_prompt": plan_prompt}
    return result, state.update(**result)
    ```