code: def test_collect():
      a = {"x": 1, "y": {"a": 1}}
      b = {"x": 2, "z": 3, "y": {"b": 2}}
      env = {"DASK_W": "4"}
  
      expected = {"w": 4, "x": 2, "y": {"a": 1, "b": 2}, "z": 3}
  
      with tmpfile(extension="yaml") as fn1:
          with tmpfile(extension="yaml") as fn2:
              with open(fn1, "w") as f:
                  yaml.dump(a, f)
              with open(fn2, "w") as f:
                  yaml.dump(b, f)
  
              config = collect([fn1, fn2], env=env)
              assert config == expected
  
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 16 for calling a global function with example usage: test_collect() without return types