code: def test_no_changes(tmp_dir, scm, dvc):
      tmp_dir.dvc_gen("file", "first", commit="add a file")
      assert dvc.diff() == {}
  
imports: import hashlib
  import os
  import pytest
  from funcy import first
  from dvc.exceptions import DvcException
  from dvc.utils.fs import remove
label_desc: Use image node_id 14 for calling a global function with example usage: test_no_changes(tmp_dir, scm, dvc) without return types