class_docstr: Defined by J. Welles Wilder, Jr. in 1978 in his book *"New Concepts in
  Technical Trading Systems"*.
  
  The idea is to take the close into account to calculate the range if it
  yields a larger range than the daily range (High - Low)
  
  Formula:
    - SmoothedMovingAverage(TrueRange, period)
  
  See:
    - http://en.wikipedia.org/wiki/Average_true_range
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code: def _plotlabel(self):
      plabels = [self.p.period]
      plabels += [self.p.movav] * self.p.notdefault("movav")
      return plabels
  
file_path: backtrader/backtrader/indicators/atr.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from .None import Indicator, Max, Min, MovAv
label_desc: Use image node_id 1 for calling the AverageTrueRange obj's underlying member method code with example usage: obj._plotlabel() and returns: plabels