code: def test_duration_std_var() -> None:
      df = pl.DataFrame(
          {"duration": [10, 5, 3]}, schema={"duration": pl.Duration}
      )
  
      result = df.select(
          pl.col("duration").var().name.suffix("_var"),
          pl.col("duration").std().name.suffix("_std"),
      )
  
      expected = pl.DataFrame(
          [
              pl.Series(
                  "duration_var",
                  [timedelta(microseconds=13)],
                  dtype=pl.Duration(time_unit="us"),
              ),
              pl.Series(
                  "duration_std",
                  [timedelta(microseconds=3)],
                  dtype=pl.Duration(time_unit="us"),
              ),
          ]
      )
  
      assert_frame_equal(result, expected)
  
imports: from datetime import timedelta
  import polars
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 2 for calling a global function with example usage: test_duration_std_var() without return types