code: def testEmpty(self):
      ds = bards.BarDataSeries()
      with self.assertRaises(IndexError):
          ds[-1]
      with self.assertRaises(IndexError):
          ds[0]
      with self.assertRaises(IndexError):
          ds[1000]
  
imports: import datetime
  from six.moves import xrange
  from .None import common
  from pyalgotrade import dataseries
  from pyalgotrade.dataseries import bards
  from pyalgotrade.dataseries import aligned
  from pyalgotrade import bar
label_desc: Use image node_id 1 for calling the TestBarDataSeries obj's underlying member method code with example usage: obj.testEmpty() without return types