code: def testATR(self):
      barDs = self.__loadBarDS()
      self.assertAmountsAreEqual(
          indicator.ATR(barDs, 252, 1)[1], 3.535, 3
      )
      self.assertAmountsAreEqual(
          indicator.ATR(barDs, 252, 1)[13], 9.685, 3
      )
      self.assertAmountsAreEqual(
          indicator.ATR(barDs, 252, 1)[41], 5.125, 3
      )
      self.assertAmountsAreEqual(
          indicator.ATR(barDs, 252, 1)[-1], 2.88, 3
      )
  
imports: import datetime
  import talib
  from six.moves import xrange
  from .None import common
  from pyalgotrade.talibext import indicator
  from pyalgotrade import bar
  from pyalgotrade import dataseries
  from pyalgotrade.dataseries import bards
label_desc: Use image node_id 12 for calling the TestCase obj's underlying member method code with example usage: obj.testATR() without return types