code: def test_du(tmp_dir, dvc):
      tmp_dir.gen(
          {
              "file": b"file",
              "dvcfile": b"dvcfile",
              "dir": {
                  "dirfile": b"dirfile",
                  "subdir": {
                      "subdirfile": b"subdirfile",
                  },
                  "dvcsubdir": {
                      "dvcsubdirfile": b"dvcsubdirfile",
                  },
              },
          }
      )
  
      dvc.add("dvcfile")
      dvc.add(os.path.join("dir", "dvcsubdir"))
  
      assert dvc.du(".", "file") == [("file", 4)]
      assert dvc.du(".", "dvcfile") == [("dvcfile", 7)]
      assert set(dvc.du(".", "dir/subdir")) == {
          ("dir/subdir/subdirfile", 10),
          ("dir/subdir", 10),
      }
      assert dvc.du(".", "dir/subdir", summarize=True) == [
          ("dir/subdir", 10)
      ]
      assert set(dvc.du(".", "dir/dvcsubdir")) == {
          ("dir/dvcsubdir/dvcsubdirfile", 13),
          ("dir/dvcsubdir", 13),
      }
      assert dvc.du(".", "dir/dvcsubdir", summarize=True) == [
          ("dir/dvcsubdir", 13)
      ]
      assert set(dvc.du(".", "dir")) == {
          ("dir/dvcsubdir", 13),
          ("dir/subdir", 10),
          ("dir/dirfile", 7),
          ("dir", 30),
      }
      assert dvc.du(".", "dir", summarize=True) == [("dir", 30)]
      assert set(dvc.du(".", "/")) == {
          ("/dvcfile", 7),
          ("/dir", 30),
          ("/file", 4),
          ("/", 41),
      }
      assert dvc.du(".", "/", summarize=True) == [("/", 41)]
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_du(tmp_dir, dvc) without return types