code: def test_kvo_ext(self):
      self.data.ta.kvo(append=True)
      self.assertIsInstance(self.data, DataFrame)
      self.assertEqual(
          list(self.data.columns[-2:]),
          ["KVO_34_55_13", "KVOs_34_55_13"],
      )
  
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 12 for calling the TestVolumeExtension obj's underlying member method code with example usage: obj.test_kvo_ext() without return types