code: def __init__(self):
      h0l1 = abs(self.data.high(0) - self.data.low(-1))
      vm_plus = bt.ind.SumN(h0l1, period=self.p.period)
  
      l0h1 = abs(self.data.low(0) - self.data.high(-1))
      vm_minus = bt.ind.SumN(l0h1, period=self.p.period)
  
      h0c1 = abs(self.data.high(0) - self.data.close(-1))
      l0c1 = abs(self.data.low(0) - self.data.close(-1))
      h0l0 = abs(self.data.high(0) - self.data.low(0))
  
      tr = bt.ind.SumN(bt.Max(h0l0, h0c1, l0c1), period=self.p.period)
  
      self.l.vi_plus = vm_plus / tr
      self.l.vi_minus = vm_minus / tr
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import backtrader
label_desc: Use image node_id 1 to create a new Vortex object from inherited base classes: bt with example: obj = Vortex()