code: def test_diff_exp(tmp_dir, scm, dvc, exp_stage):
      results = dvc.experiments.run(
          exp_stage.addressing, params=["foo=2"]
      )
      exp_a = first(results)
      results = dvc.experiments.run(
          exp_stage.addressing, params=["foo=3"]
      )
      exp_b = first(results)
  
      assert dvc.experiments.diff(a_rev=exp_a, b_rev=exp_b) == {
          "params": {
              "params.yaml": {"foo": {"diff": 1, "old": 2, "new": 3}}
          },
          "metrics": {
              "metrics.yaml": {"foo": {"diff": 1, "old": 2, "new": 3}}
          },
      }
  
label_desc: Use image node_id 3 for calling a global function with example usage: test_diff_exp(tmp_dir, scm, dvc, exp_stage) without return types