code: def test_no_levels_does_no_change():
      """Test that if num_levels = 0 then no change occurs."""
      X = _make_nested_from_array(
          np.array([1, 2, 3, 4, 5, 56]), n_instances=1, n_columns=1
      )
      d = DWTTransformer(num_levels=0).fit(X)
      res = d.transform(X)
      assert check_if_dataframes_are_equal(res, X)
  
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 3 for calling a global function with example usage: test_no_levels_does_no_change() without return types