code: def num_connected_contexts():
      """Return the number of client connections active."""
      global _lock, _all_contexts
      with _lock:
          return len(_all_contexts)
  
imports: import logging
  import os
  import sys
  import threading
  from typing import Any, Dict, List, Optional, Tuple
  import ray._private.ray_constants
  from ray._private.client_mode_hook import _explicitly_disable_client_mode, _explicitly_enable_client_mode
  from ray._private.ray_logging import setup_logger
  from ray.job_config import JobConfig
  from ray.util.annotations import DeveloperAPI
label_desc: Use image node_id 1 for calling a global function with example usage: num_connected_contexts() and returns: len