code: def test_output_of_transformer():
      """Test that the transformer has changed the data correctly."""
      X = _make_nested_from_array(
          np.array([4, 6, 10, 12, 8, 6, 5, 5]),
          n_instances=1,
          n_columns=1,
      )
  
      d = DWTTransformer(num_levels=2).fit(X)
      res = d.transform(X)
      orig = convert_list_to_dataframe(
          [
              [
                  16,
                  12,
                  -6,
                  2,
                  -math.sqrt(2),
                  -math.sqrt(2),
                  math.sqrt(2),
                  0,
              ]
          ]
      )
      orig.columns = X.columns
      assert check_if_dataframes_are_equal(res, orig)
  
      X = _make_nested_from_array(
          np.array([-5, 2.5, 1, 3, 10, -1.5, 6, 12, -3]),
          n_instances=1,
          n_columns=1,
      )
      d = d.fit(X)
      res = d.transform(X)
      orig = convert_list_to_dataframe(
          [
              [
                  0.75000,
                  13.25000,
                  -3.25000,
                  -4.75000,
                  -5.303301,
                  -1.414214,
                  8.131728,
                  -4.242641,
              ]
          ]
      )
  
file_path: sktime/sktime/transformations/panel/tests/test_dwt.py
imports: import math
  import numpy
  import pandas
  import pytest
  from sktime.transformations.panel.dwt import DWTTransformer
  from sktime.utils._testing.panel import _make_nested_from_array
label_desc: Use image node_id 2 for calling a global function with example usage: test_output_of_transformer() without return types