code: def testInvalidDateTimes(self):
      b1 = bar.BasicBar(
          datetime.datetime.now(),
          2,
          3,
          1,
          2.1,
          10,
          5,
          bar.Frequency.DAY,
      )
      b2 = bar.BasicBar(
          datetime.datetime.now() + datetime.timedelta(days=1),
          2,
          3,
          1,
          2.1,
          10,
          5,
          bar.Frequency.DAY,
      )
      with self.assertRaises(Exception):
          bar.Bars({"a": b1, "b": b2})
  
file_path: pyalgotrade/testcases/bar_test.py
imports: import datetime
  from six.moves import cPickle
  from .None import common
  from pyalgotrade import bar
label_desc: Use image node_id 2 for calling the BarsTestCase obj's underlying member method code with example usage: obj.testInvalidDateTimes() without return types