code: def setUp(self):
      thread_num = os.environ.get("THREAD_NUM")
      if thread_num is not None:
          self.n_threads = int(thread_num)
      else:
          self.n_threads = 2
  
file_path: BigDL/python/llm/test/inference/test_optimize.py
imports: import unittest
  import os
  import pytest
  import time
  import torch
  from bigdl.llm import optimize_model
label_desc: Use image node_id 1 for calling the TestOptimizeAPI obj's underlying member method code with example usage: obj.setUp() without return types