code: def __init__(self, metadata):
      # -- Read only variables --
      self.metadata = metadata
      self.sample_batch = 1000000
      # -- Variables that are accessed by mulitple threads --
      self.lock = threading.Lock()
      self.result_queue = Queue()
      self.is_running = False
  
imports: import argparse
  import json
  import logging
  import numpy
  import os
  import threading
  import time
  from ray._private.test_utils import monitor_memory_usage
  from ray.data._internal.progress_bar import ProgressBar
  from collections import namedtuple
  from queue import Queue
  import ray
label_desc: Use image node_id 1 to create a new PiCalculator object  with example: obj = PiCalculator(metadata)