code: def test_refresh():
      defaults = []
      config = {}
  
      update_defaults({"a": 1}, config=config, defaults=defaults)
      assert config == {"a": 1}
  
      refresh(
          paths=[],
          env={"DASK_B": "2"},
          config=config,
          defaults=defaults,
      )
      assert config == {"a": 1, "b": 2}
  
      refresh(
          paths=[],
          env={"DASK_C": "3"},
          config=config,
          defaults=defaults,
      )
      assert config == {"a": 1, "c": 3}
  
imports: from __future__ import annotations
  import os
  import site
  import stat
  import sys
  from collections import OrderedDict
  from contextlib import contextmanager
  import pytest
  import yaml
  import dask.config
  from dask.config import _get_paths, canonical_name, collect, collect_env, collect_yaml, config, deserialize, ensure_file, expand_environment_variables, get, merge, pop, refresh, rename, serialize, update, update_defaults
  from dask.utils import tmpfile
label_desc: Use image node_id 27 for calling a global function with example usage: test_refresh() without return types