code: def test_vp_ext(self):
      result = self.data.ta.vp()
      self.assertIsInstance(result, DataFrame)
      self.assertEqual(result.name, "VP_10")
  
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 20 for calling the TestVolumeExtension obj's underlying member method code with example usage: obj.test_vp_ext() without return types