def test_sub_timedelta(self):
    'Test subtracting a timedelta from a Timestamp.'
    t1 = Timestamp.utcnow()
    t2 = (t1 - datetime.timedelta(days=1))
    if (t1.month != t2.month):
        self.assertEqual(calendar.monthrange(t2.year, t2.month)[1], t2.day)
    else:
        self.assertEqual((t1.day - 1), t2.day)
    self.assertIsInstance(t2, Timestamp)
Test subtracting a timedelta from a Timestamp.
def test_sub_timedelta(self):
    
    t1 = Timestamp.utcnow()
    t2 = (t1 - datetime.timedelta(days=1))
    if (t1.month != t2.month):
        self.assertEqual(calendar.monthrange(t2.year, t2.month)[1], t2.day)
    else:
        self.assertEqual((t1.day - 1), t2.day)
    self.assertIsInstance(t2, Timestamp)