code: def test_env_var_enables_ray_debugger():
      with unittest.mock.patch.dict(os.environ):
          os.environ["RAY_PDB"] = "1"
          assert (
              ray.util.pdb._is_ray_debugger_enabled()
          ), "Expected Ray Debugger to be enabled when RAY_PDB env var is present."
  
      with unittest.mock.patch.dict(os.environ):
          if "RAY_PDB" in os.environ:
              del os.environ["RAY_PDB"]
  
          assert (
              not ray.util.pdb._is_ray_debugger_enabled()
          ), "Expected Ray Debugger to be disabled when RAY_PDB env var is absent."
  
imports: import json
  import os
  import platform
  import subprocess
  import sys
  from telnetlib import Telnet
  import unittest
  import pexpect
  import pytest
  import ray
  from ray._private import ray_constants, services
  from ray._private.test_utils import run_string_as_driver, wait_for_condition
  from ray.cluster_utils import Cluster, cluster_not_supported
label_desc: Use image node_id 8 for calling a global function with example usage: test_env_var_enables_ray_debugger() without return types