code: def testEmpty(self):
      ds = dataseries.SequenceDataSeries()
      self.assertTrue(len(ds) == 0)
      with self.assertRaises(IndexError):
          ds[-1]
      with self.assertRaises(IndexError):
          ds[-2]
      with self.assertRaises(IndexError):
          ds[0]
      with self.assertRaises(IndexError):
          ds[1]
  
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 TestSequenceDataSeries obj's underlying member method code with example usage: obj.testEmpty() without return types