def METHOD_NAME(self):
    r"""
    Checking utility: display_multiset
    """
    self.assertEqual(display_multiset([["a", 3], [12, 2]]), 'a x3, 12 x2')
    self.assertEqual(display_multiset([[1, 4], [0, 0], ["cat", 2]]),
                                      '1 x4, 0, cat x2')