'Deleting an item, then inserting the same key again will place it
at the end.'

def test_delete_and_insert(self):

    del self.d2[7]
    self.assertEqual(self.d2.keys(), [1, 9, 0])
    self.d2[7] = 'lucky    number    7'
    self.assertEqual(self.d2.keys(), [1, 9, 0, 7])
