class_docstr: Developed by Larry Williams to show the relation of closing prices to
  the highest-lowest range of a given period.
  
  Known as Williams %R (but % is not allowed in Python identifiers)
  
  Formula:
    - num = highest_period - close
    - den = highestg_period - lowest_period
    - percR = (num / den) * -100.0
  
  See:
    - http://en.wikipedia.org/wiki/Williams_%25R
code: def __init__(self):
      h = Highest(self.data.high, period=self.p.period)
      l = Lowest(self.data.low, period=self.p.period)
      c = self.data.close
  
      self.lines.percR = -100.0 * (h - c) / (h - l)
  
      super(WilliamsR, self).__init__()
  
file_path: backtrader/backtrader/indicators/williams.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from .None import Indicator, Highest, Lowest, If, UpDay, DownDay, Accum, TrueLow, TrueHigh
label_desc: Use image node_id 2 to create a new WilliamsR object from inherited base classes: Indicator with example: obj = WilliamsR()