code: def test_simpleseries_constant_season():
      df = make_simpleseries(
          n_samples=365 * 2,
          as_frame=True,
          start_date="2018-01-01",
          trend=0,
          noise=0,
          season_trend=0,
      ).assign(
          month=lambda d: d["date"].dt.month,
          year=lambda d: d["date"].dt.year,
      )
      agg = df.groupby(["year", "month"]).mean().reset_index()
      var = agg.loc[lambda d: d["month"] == 1]["yt"].var()
      assert var == pytest.approx(0.0, abs=0.01)
  
file_path: scikit-lego/tests/test_datasets.py
imports: import pytest
  from sklego.datasets import load_abalone, load_chicken, load_hearts, load_penguins, make_simpleseries
label_desc: Use image node_id 5 for calling a global function with example usage: test_simpleseries_constant_season() without return types