code: def get_hub_url():
      return os.getenv(ENV_TOWHEE_URL, _HUB_URL)
  
imports: import os
  import sys
  import tempfile
  import shutil
  from pathlib import Path
  from concurrent.futures import ThreadPoolExecutor
  import subprocess
  import requests
  from tqdm import tqdm
  from tenacity import retry, stop_after_attempt, wait_random_exponential
  from towhee.utils.hub_utils import HubUtils
label_desc: Use image node_id 2 for calling a global function with example usage: get_hub_url() and returns: os