code: def test_label():
      assert label("x") == "x"
      assert (
          label("elemwise-ffcd9aa2231d466b5aa91e8bfa9e9487")
          == "elemwise-#"
      )
  
      cache = {}
      result = label(
          "elemwise-ffcd9aa2231d466b5aa91e8bfa9e9487", cache=cache
      )
      assert result == "elemwise-#0"
      # cached
      result = label(
          "elemwise-ffcd9aa2231d466b5aa91e8bfa9e9487", cache=cache
      )
      assert result == "elemwise-#0"
      assert len(cache) == 1
  
      result = label(
          "elemwise-e890b510984f344edea9a5e5fe05c0db", cache=cache
      )
      assert result == "elemwise-#1"
      assert len(cache) == 2
  
      result = label(
          "elemwise-ffcd9aa2231d466b5aa91e8bfa9e9487", cache=cache
      )
      assert result == "elemwise-#0"
      assert len(cache) == 2
  
      assert label("x", cache=cache) == "x"
      assert len(cache) == 2
  
imports: from __future__ import annotations
  import copy
  import os
  import re
  import sys
  from functools import partial
  from operator import add, neg
  import pytest
  from dask.dot import _to_cytoscape_json, cytoscape_graph
  from dask import delayed
  from dask.utils import ensure_not_exists
label_desc: Use image node_id 4 for calling a global function with example usage: test_label() without return types