code: def fast_gcs_failure_detection():
      # This ensures that these environment vars are not set.
      assert "GCS_CHECK_ALIVE_MAX_COUNT_OF_RPC_ERROR" not in os.environ
      assert "GCS_CHECK_ALIVE_INTERVAL_SECONDS" not in os.environ
      assert "GCS_RETRY_CONNECT_INTERVAL_SECONDS" not in os.environ
  
      os.environ["GCS_CHECK_ALIVE_MAX_COUNT_OF_RPC_ERROR"] = "2"
      os.environ["GCS_CHECK_ALIVE_INTERVAL_SECONDS"] = "1"
      os.environ["GCS_RETRY_CONNECT_INTERVAL_SECONDS"] = "1"
      os.environ["GCS_CHECK_ALIVE_RPC_TIMEOUT"] = "1"
      yield
      os.environ.pop("GCS_CHECK_ALIVE_MAX_COUNT_OF_RPC_ERROR", None)
      os.environ.pop("GCS_CHECK_ALIVE_INTERVAL_SECONDS", None)
      os.environ.pop("GCS_RETRY_CONNECT_INTERVAL_SECONDS", None)
      os.environ.pop("GCS_CHECK_ALIVE_RPC_TIMEOUT", None)
  
file_path: ray/python/ray/dashboard/tests/conftest.py
imports: import os
  import pytest
  import pathlib
  from ray.tests.conftest import *
label_desc: Use image node_id 4 for calling a global function with example usage: fast_gcs_failure_detection() without return types