code: def test_time_rolling_constructor():
      result = dts.rolling("4s")
      assert result.window == "4s"
      assert result.min_periods is None
      assert result.win_type is None
  
      if not dd._dask_expr_enabled():
          assert result._win_type == "freq"
  
imports: from __future__ import annotations
  import contextlib
  import datetime
  import numpy
  import pandas
  import pytest
  import dask.dataframe
  from dask.dataframe._compat import PANDAS_GE_210
  from dask.dataframe.utils import assert_eq
label_desc: Use image node_id 16 for calling a global function with example usage: test_time_rolling_constructor() without return types