class_docstr: http://stockcharts.com/school/doku.php?id=chart_school:technical_indicators:commodity_channel_index_cci
class_docstr_tok: ["http",":","\/\/stockcharts.com\/school\/doku.php","?","id=chart_school",":","technical_indicators",":","commodity_channel_index_cci"]
code: def test_vortex_indicator_neg(self):
      target = "-VI14"
      result = vortex_indicator_neg(**self._params)
      pd.testing.assert_series_equal(
          self._df[target].tail(), result.tail(), check_names=False
      )
  
imports: import unittest
  import pandas
  from ta.trend import MACD, ADXIndicator, CCIIndicator, PSARIndicator, STCIndicator, VortexIndicator, WMAIndicator, adx, adx_neg, adx_pos, cci, macd, macd_diff, macd_signal, psar_down, psar_down_indicator, psar_up, psar_up_indicator, stc, vortex_indicator_neg, vortex_indicator_pos, wma_indicator
label_desc: Use image node_id 5 for calling the TestVortexIndicator obj's underlying member method code with example usage: obj.test_vortex_indicator_neg() without return types