code: def test_extraction_null_as_column_name(self):
      df1 = pd.DataFrame(
          data={
              0: range(10),
              1: np.repeat([0, 1], 5),
              2: np.repeat([0, 1, 2, 3, 4], 2),
          }
      )
      X1 = extract_features(df1, column_id=1, column_sort=2)
      self.assertEqual(len(X1), 2)
  
      df2 = pd.DataFrame(
          data={
              1: range(10),
              0: np.repeat([0, 1], 5),
              2: np.repeat([0, 1, 2, 3, 4], 2),
          }
      )
      X2 = extract_features(df2, column_id=0, column_sort=2)
      self.assertEqual(len(X2), 2)
  
      df3 = pd.DataFrame(
          data={
              0: range(10),
              2: np.repeat([0, 1], 5),
              1: np.repeat([0, 1, 2, 3, 4], 2),
          }
      )
      X3 = extract_features(df3, column_id=2, column_sort=1)
      self.assertEqual(len(X3), 2)
  
file_path: tsfresh/tests/integrations/test_relevant_feature_extraction.py
imports: from unittest import TestCase
  import numpy
  import pandas
  import pandas.testing
  from tests.fixtures import DataTestCase
  from tsfresh import extract_features, extract_relevant_features, select_features
  from tsfresh.feature_extraction.settings import ComprehensiveFCParameters
  from tsfresh.utilities.dataframe_functions import impute
label_desc: Use image node_id 3 for calling the RelevantFeatureExtractionTestCase obj's underlying member method code with example usage: obj.test_extraction_null_as_column_name() without return types