code: def test_get():
      d = {"x": 1, "y": {"a": 2}}
  
      assert get("x", config=d) == 1
      assert get("y.a", config=d) == 2
      assert get("y.b", 123, config=d) == 123
      with pytest.raises(KeyError):
          get("y.b", config=d)
  
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 18 for calling a global function with example usage: test_get() without return types