def test_ts_windowtransf_drop_hierarchy(self, transforms):
        """Checking that hierarchy is correctly removed when
        - transform is not applied to all the components
        - several transforms applied to all the components
        - two transforms with overlapping components
        """
        ts = helper_generate_ts_hierarchy(10)
        ts_tr = ts.window_transform(transforms=transforms)
        assert ts_tr.hierarchy is None
Checking that hierarchy is correctly removed when
        - transform is not applied to all the components
        - several transforms applied to all the components
        - two transforms with overlapping components
        
darts/tests/dataprocessing/transformers/test_window_transformations.py