def METHOD_NAME():
    # Make sure constant value timeseries is not truncated.
    values = [100_000] * 28
    ds_in = test_helpers.build_default_region_dataset({CommonFields.CASES: values})
    tail_filter, ds_out = TailFilter.run(ds_in, [CommonFields.CASES])
    _assert_tail_filter_counts(tail_filter, all_good=1)
    test_helpers.assert_dataset_like(ds_out, ds_in, drop_na_dates=True)