code: def test_thermo_ext(self):
      self.data.ta.thermo(append=True)
      self.assertIsInstance(self.data, DataFrame)
      self.assertEqual(
          list(self.data.columns[-4:]),
          [
              "THERMO_20_2_0.5",
              "THERMOma_20_2_0.5",
              "THERMOl_20_2_0.5",
              "THERMOs_20_2_0.5",
          ],
      )
  
imports: from .config import sample_data
  from .context import pandas_ta
  from unittest import TestCase
  from pandas import DataFrame
label_desc: Use image node_id 17 for calling the TestVolatilityExtension obj's underlying member method code with example usage: obj.test_thermo_ext() without return types