code: def test_sort_key():
      L = ["x", ("x", 1), ("z", 0), ("x", 0)]
      assert sorted(L, key=sortkey) == [
          "x",
          ("x", 0),
          ("x", 1),
          ("z", 0),
      ]
  
imports: from __future__ import annotations
  import pytest
  import dask
  from dask.local import finish_task, get_sync, sortkey, start_state_from_dask
  from dask.order import order
  from dask.utils_test import GetFunctionTestMixin, add, inc
label_desc: Use image node_id 8 for calling a global function with example usage: test_sort_key() without return types