code: def start(self):
      self.start_time = time.time()
  
imports: import argparse
  import ast
  import os
  import signal
  import threading
  import time
  from typing import Dict, List, Optional, Union
  import torch
  from fairseq import distributed_utils, tasks, utils
  from pytorch_translate.file_io import PathManager
label_desc: Use image node_id 2 for calling the BucketStopwatchMeter obj's underlying member method code with example usage: obj.start() without return types